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http://www.odci.gov/cia/reports/nie/report/nie99-17d.html
The Global Infectious Disease Threat and Its Implications for
the United States
NIE 99-17D, January 2000
The Estimate was produced under the auspices of David F. Gordon,
National Intelligence Officer for Economics and Global Issues. The
primary drafters were Lt. Col. (Dr.) Don Noah of the Armed Forces
Medical Intelligence Center and George Fidas of the NIC. The
Estimate also benefited from a conference on infectious diseases
held jointly with the State Department's Bureau of Intelligence and
Research, and was reviewed by several prominent epidemiologists and
other health experts in and outside the US Government. We hope that
it will further inform the debate about this important subject.
John C. Gannon
Chairman, National Intelligence Council
Preface
The Global Infectious Disease Threat and Its Implications for
the United States
I am pleased to share with you this unclassified version of a new
National Intelligence Estimate on the reemergence of the threat from
infectious diseases worldwide and its implications for the United
States.
This report represents an important initiative on the part of the
Intelligence Community to consider the national security dimension
of a nontraditional threat. It responds to a growing concern by
senior US leaders about the implications--in terms of health,
economics, and national security--of the growing global infectious
disease threat. The dramatic increase in drug-resistant microbes,
combined with the lag in development of new antibiotics, the rise of
megacities with severe health care deficiencies, environmental
degradation, and the growing ease and frequency of cross-border
movements of people and produce have greatly facilitated the spread
of infectious diseases.
In June 1996, President Clinton issued a Presidential Decision
Directive calling for a more focused US policy on infectious
diseases. The State Department's Strategic Plan for International
Affairs lists protecting human health and reducing the spread of
infectious diseases as US strategic goals, and Secretary Albright in
December 1999 announced the second of two major U.S. initiatives to
combat HIV/AIDS. The unprecedented UN Security Council session
devoted exclusively to the threat to Africa from HIV/AIDS in January
2000 is a measure of the international community's concern about the
infectious disease threat.
As part of this new US Government effort, the National
Intelligence Council produced this National Intelligence Estimate.
It examines the most lethal diseases globally and by region;
develops alternative scenarios about their future course; examines
national and international capacities to deal with them; and
assesses their national and global social, economic, political, and
security impact. It then assesses the infectious disease threat from
international sources to the United States; to US military personnel
overseas; and to regions in which the United States has or may
develop significant equities.
Key Judgments
The Global Infectious Disease Threat and Its Implications for
the United States
New and reemerging infectious diseases will pose a rising global
health threat and will complicate US and global security over the
next 20 years. These diseases will endanger US citizens at home and
abroad, threaten US armed forces deployed overseas, and exacerbate
social and political instability in key countries and regions in
which the United States has significant interests.
Infectious diseases are a leading cause of death, accounting for
a quarter to a third of the estimated 54 million deaths worldwide in
1998. The spread of infectious diseases results as much from changes
in human behavior--including lifestyles and land use patterns,
increased trade and travel, and inappropriate use of antibiotic
drugs--as from mutations in pathogens.
- Twenty well-known diseases--including tuberculosis (TB),
malaria, and cholera--have reemerged or spread geographically
since 1973, often in more virulent and drug-resistant forms.
- At least 30 previously unknown disease agents have been
identified since 1973, including HIV, Ebola, hepatitis C, and
Nipah virus, for which no cures are available.
- Of the seven biggest killers worldwide, TB, malaria,
hepatitis, and, in particular, HIV/AIDS continue to surge, with
HIV/AIDS and TB likely to account for the overwhelming majority
of deaths from infectious diseases in developing countries by
2020. Acute lower respiratory infections--including pneumonia
and influenza--as well as diarrheal diseases and measles, appear
to have peaked at high incidence levels.
Impact Within the United States
Although the infectious disease threat in the United States
remains relatively modest as compared to that of noninfectious
diseases, the trend is up. Annual infectious disease-related death
rates in the United States have nearly doubled to some 170,000
annually after reaching an historic low in 1980. Many infectious
diseases--most recently, the West Nile virus--originate outside US
borders and are introduced by international travelers, immigrants,
returning US military personnel, or imported animals and foodstuffs.
In the opinion of the US Institute of Medicine, the next major
infectious disease threat to the United States may be, like HIV, a
previously unrecognized pathogen. Barring that, the most dangerous
known infectious diseases likely to threaten the United States over
the next two decades will be HIV/AIDS, hepatitis C, TB, and new,
more lethal variants of influenza. Hospital-acquired infections and
foodborne illnesses also will pose a threat.
- Although multidrug therapies have cut HIV/AIDS
deaths by two-thirds to 17,000 annually since 1995, emerging
microbial resistance to such drugs and continued new infections
will sustain the threat.
- Some 4 million Americans are chronic carriers of the
hepatitis C virus, a significant cause of liver cancer
and cirrhosis. The US death toll from the virus may surpass that
of HIV/AIDS in the next five years.
- TB, exacerbated by multidrug resistant strains
and HIV/AIDS co-infection, has made a comeback. Although a
massive and costly control effort is achieving considerable
success, the threat will be sustained by the spread of HIV and
the growing number of new, particularly illegal, immigrants
infected with TB.
- Influenza now kills some 30,000 Americans
annually, and epidemiologists generally agree that it is not a
question of whether, but when, the next killer pandemic will
occur.
- Highly virulent and increasingly antimicrobial
resistant pathogens, such as Staphylococcus aureus,
are major sources of hospital-acquired infections that kill some
14,000 patients annually.
- The doubling of US food imports over the last five years is
one of the factors contributing to tens of millions of
foodborne illnesses and 9,000 deaths that occur
annually, and the trend is up.
Regional Trends
Developing and former communist countries will continue to
experience the greatest impact from infectious diseases--because of
malnutrition, poor sanitation, poor water quality, and inadequate
health care--but developed countries also will be affected:
- Sub-Saharan Africa--accounting for nearly half of
infectious disease deaths globally--will remain the most
vulnerable region. The death rates for many diseases, including
HIV/AIDS and malaria, exceed those in all other regions.
Sub-Saharan Africa's health care capacity--the poorest in the
world--will continue to lag.
- Asia and the Pacific, where multidrug resistant TB,
malaria, and cholera are rampant, is likely to witness a
dramatic increase in infectious disease deaths, largely driven
by the spread of HIV/AIDS in South and Southeast Asia and its
likely spread to East Asia. By 2010, the region could surpass
Africa in the number of HIV infections.
- The former Soviet Union (FSU) and, to a lesser
extent, Eastern Europe also are likely to see a substantial
increase in infectious disease incidence and deaths. In the FSU
especially, the steep deterioration in health care and other
services owing to economic decline has led to a sharp rise in
diphtheria, dysentery, cholera, and hepatitis B and C. TB has
reached epidemic proportions throughout the FSU, while the
HIV-infected population in Russia alone could exceed 1 million
by the end of 2000 and double yet again by 2002.
- Latin American countries generally are making
progress in infectious disease control, including the
eradication of polio, but uneven economic development has
contributed to widespread resurgence of cholera, malaria, TB,
and dengue. These diseases will continue to take a heavy toll in
tropical and poorer countries.
- The Middle East and North Africa region has
substantial TB and hepatitis B and C prevalence, but
conservative social mores, climatic factors, and the high level
of health spending in the oil-producing states tend to limit
some globally prevalent diseases, such as HIV/AIDS and malaria.
The region has the lowest HIV infection rate among all regions,
although this is probably due in part to above-average
underreporting because of the stigma associated with the disease
in Muslim societies.
- Western Europe faces threats from several infectious
diseases, such as HIV/AIDS, TB, and hepatitis B and C, as well
as from several economically costly zoonotic diseases (that is,
those transmitted from animals to humans). The region's large
volume of travel, trade, and immigration increases the risks of
importing diseases from other regions, but its highly developed
health care system will limit their impact.
Response Capacity
Development of an effective global surveillance and response
system probably is at least a decade or more away, owing to
inadequate coordination and funding at the international level and
lack of capacity, funds, and commitment in many developing and
former communist states. Although overall global health care
capacity has improved substantially in recent decades, the gap
between rich and poorer countries in the availability and quality of
health care, as illustrated by a typology developed by the Defense
Intelligence Agency's Armed Forces Medical Intelligence Center
(AFMIC), is widening.
Alternative Scenarios
We have examined three plausible scenarios for the course of the
infectious disease threat over the next 20 years:
Steady Progress
The least likely scenario projects steady progress whereby the aging
of global populations and declining fertility rates, socioeconomic
advances, and improvements in health care and medical breakthroughs
hasten movement toward a "health transition" in which such
noninfectious diseases as heart disease and cancer would replace
infectious diseases as the overarching global health challenge. We
believe this scenario is unlikely primarily because it gives
inadequate emphasis to persistent demographic and socioeconomic
challenges in the developing countries, to increasing microbial
resistance to existing antibiotics, and because related models have
already underestimated the force of major killers such as HIV/AIDS,
TB, and malaria.
Progress Stymied
A more pessimistic--and more plausible--scenario projects little or
no progress in countering infectious diseases over the duration of
this Estimate. Under this scenario, HIV/AIDS reaches catastrophic
proportions as the virus spreads throughout the vast populations of
India, China, the former Soviet Union, and Latin America, while
multidrug treatments encounter microbial resistance and remain
prohibitively expensive for developing countries. Multidrug
resistant strains of TB, malaria, and other infectious diseases
appear at a faster pace than new drugs and vaccines, wreaking havoc
on world health. Although more likely than the "steady progress"
scenario, we judge that this scenario also is unlikely to prevail
because it underestimates the prospects for socioeconomic
development, international collaboration, and medical and health
care advances to constrain the spread of at least some widespread
infectious diseases.
Deterioration, Then Limited Improvement
The most likely scenario, in our view, is one in which the
infectious disease threat--particularly from HIV/AIDS--worsens
during the first half of our time frame, but decreases fitfully
after that, owing to better prevention and control efforts, new
drugs and vaccines, and socioeconomic improvements. In the next
decade, under this scenario, negative demographic and social
conditions in developing countries, such as continued urbanization
and poor health care capacity, remain conducive to the spread of
infectious diseases; persistent poverty sustains the least developed
countries as reservoirs of infection; and microbial resistance
continues to increase faster than the pace of new drug and vaccine
development. During the subsequent decade, more positive demographic
changes such as reduced fertility and aging populations; gradual
socioeconomic improvement in most countries; medical advances
against childhood and vaccine-preventable killers such as diarrheal
diseases, neonatal tetanus, and measles; expanded international
surveillance and response systems; and improvements in national
health care capacities take hold in all but the least developed
countries. Barring the appearance of a deadly and highly infectious
new disease, a catastrophic upward lurch by HIV/AIDS, or the release
of a highly contagious biological agent capable of rapid and
widescale secondary spread, these developments produce at least
limited gains against the overall infectious disease threat.
However, the remaining group of virulent diseases, led by HIV/AIDS
and TB, continue to take a significant toll.
Economic, Social, and Political Impact
The persistent infectious disease burden is likely to aggravate
and, in some cases, may even provoke economic decay, social
fragmentation, and political destabilization in the hardest hit
countries in the developing and former communist worlds, especially
in the worst case scenario outlined above:
- The economic costs of infectious diseases--especially
HIV/AIDS and malaria--are already significant, and their
increasingly heavy toll on productivity, profitability, and
foreign investment will be reflected in growing GDP losses, as
well, that could reduce GDP by as much as 20 percent or more by
2010 in some Sub-Saharan African countries, according to recent
studies.
- Some of the hardest hit countries in Sub-Saharan Africa--and
possibly later in South and Southeast Asia--will face a
demographic upheaval as HIV/AIDS and associated diseases reduce
human life expectancy by as much as 30 years and kill as many as
a quarter of their populations over a decade or less, producing
a huge orphan cohort. Nearly 42 million children in 27 countries
will lose one or both parents to AIDS by 2010; 19 of the hardest
hit countries will be in Sub-Saharan Africa.
The relationship between disease and political instability is
indirect but real. A wide-ranging study on the causes of state
instability suggests that infant mortality--a good indicator of the
overall quality of life--correlates strongly with political
instability, particularly in countries that already have achieved a
measure of democracy. The severe social and economic impact of
infectious diseases is likely to intensify the struggle for
political power to control scarce state resources.
Implications for US National Security
As a major hub of global travel, immigration, and commerce with
wide-ranging interests and a large civilian and military presence
overseas, the United States and its equities abroad will remain at
risk from infectious diseases.
- Emerging and reemerging infectious diseases, many of which
are likely to continue to originate overseas, will continue to
kill at least 170,000 Americans annually. Many more could perish
in an epidemic of influenza or yet-unknown disease or if there
is a substantial decline in the effectiveness of available
HIV/AIDS drugs.
- Infectious diseases are likely to continue to account for
more military hospital admissions than battlefield injuries. US
military personnel deployed at NATO and US bases overseas, will
be at low-to-moderate risk. At highest risk will be US military
forces deployed in support of humanitarian and peacekeeping
operations in developing countries.
- The infectious disease burden will weaken the military
capabilities of some countries--as well as international
peacekeeping efforts--as their armies and recruitment pools
experience HIV infection rates ranging from 10 to 60 percent.
The cost will be highest among officers and the more modernized
militaries in Sub-Saharan Africa and increasingly among FSU
states and possibly some rogue states.
- Infectious diseases are likely to slow socioeconomic
development in the hardest-hit developing and former communist
countries and regions. This will challenge democratic
development and transitions and possibly contribute to
humanitarian emergencies and civil conflicts.
- Infectious disease-related embargoes and restrictions on
travel and immigration will cause frictions among and between
developed and developing countries.
- The probability of a bioterrorist attack against US civilian
and military personnel overseas or in the United States also is
likely to grow as more states and groups develop a biological
warfare capability. Although there is no evidence that the
recent West Nile virus outbreak in New York City was caused by
foreign state or nonstate actors, the scare and several earlier
instances of suspected bioterrorism showed the confusion and
fear they can sow regardless of whether or not they are
validated.
Figure 1
Leading Causes of Death, 1998
Discussion
Patterns of Infectious Diseases
Broad advances in controlling or eradicating a growing number of
infectious diseases--such as tuberculosis (TB), malaria, and
smallpox--in the decades after the Second World War fueled hopes
that the global infectious disease threat would be increasingly
manageable. Optimism regarding the battle against infectious
diseases peaked in 1978 when the United Nations (UN) member states
signed the "Health for All 2000" accord, which predicted that even
the poorest nations would undergo a health transition before the
millennium, whereby infectious diseases no longer would pose a major
danger to human health. As recently as 1996, a World Bank/World
Health Organization (WHO)-sponsored study by Christopher J.L. Murray
and Alan D. Lopez projected a dramatic reduction in the infectious
disease threat. This optimism, however, led to complacency and
overlooked the role of such factors as expanded trade and travel and
growing microbial resistance to existing antibiotics in the spread
of infectious diseases. Today:
- Infectious diseases remain a leading cause of death (see
figure 1). Of the estimated 54 million deaths worldwide in 1998,
about one-fourth to one-third were due to infectious diseases,
most of them in developing countries and among children
globally.
- Infectious diseases accounted for 41 percent of the global
disease burden measured in terms of Disability-Adjusted Life
Years (DALYS) that gauge the impact of both deaths and
disabilities, as compared to 43 percent for noninfectious
diseases and 16 percent for injuries.
- Although there has been continuing progress in controlling
some vaccine-preventable childhood diseases such as polio,
neonatal tetanus, and measles, a White House-appointed
interagency working group identified at least 29 previously
unknown diseases that have appeared globally since 1973, many of
them incurable, including HIV/AIDS, Ebola hemorrhagic fever, and
hepatitis C. Most recently, Nipah encephalitis was identified.
Twenty well-known diseases such as malaria, TB, cholera, and
dengue have rebounded after a period of decline or spread to new
regions, often in deadlier forms (see table 1).
- These trends are reflected in the United States as well,
where annual infectious disease deaths have nearly doubled to
some 170,000 since 1980 after reaching historic lows that year,
while new and existing pathogens, such as HIV and West Nile
virus, respectively, continue to enter US borders.
Table 1
Examples of Pathogenic Microbes and the Diseases
They Cause, Identified Since 1973
|
| Year |
Microbe |
Type |
Disease |
| 1973 |
Rotavirus |
Virus |
Infantile diarrhea |
| 1977 |
Ebola virus |
Virus |
Acute hemorrhagic fever |
| 1977 |
Legionella pneumophila |
Bacterium |
Legionnaires' disease |
| 1980 |
Human T-lymphotrophic
virus I (HTLV 1) |
Virus |
T-cell lymphoma/leukemia |
| 1981 |
Toxin-producing
Staphylococcus aureus |
Bacterium |
Toxic shock syndrome |
| 1982 |
Escherichia coli O157:H7 |
Bacterium |
Hemorrhagic colitis; hemolytic uremic syndrome |
| 1982 |
Borrelia burgdorferi |
Bacterium |
Lyme disease |
| 1983 |
Human Immunodeficiency
Virus (HIV) |
Virus |
Acquired Immuno-Deficiency Syndrome (AIDS) |
| 1983 |
Helicobacter pylori |
Bacterium
|
Peptic ulcer disease
|
| 1989 |
Hepatitis C |
Virus |
Parentally transmitted non-A, non-B liver infection |
| 1992 |
Vibrio cholerae O139 |
Bacterium
|
New strain associated with epidemic cholera
|
| 1993 |
Hantavirus |
Virus
|
Adult respiratory distress syndrome
|
| 1994 |
Cryptosporidium |
Protozoa |
Enteric disease |
| 1995 |
Ehrlichiosis |
Bacterium |
Severe arthritis? |
| 1996 |
nvCJD |
Prion |
New variant Creutzfeldt-Jakob disease |
| 1997 |
HVN1 |
Virus |
Influenza |
| 1999 |
Nipah |
Virus |
Severe encephalitis |
Source: US Institute of Medicine, 1997; WHO, 1999.
The Deadly Seven
The seven infectious diseases that caused the highest number of
deaths in 1998, according to WHO and DIA's Armed Forces Medical
Intelligence Center (AFMIC), will remain threats well into the next
century. HIV/AIDS, TB, malaria, and hepatitis B and C--are either
spreading or becoming more drug-resistant, while lower respiratory
infections, diarrheal diseases, and measles, appear to have at least
temporarily peaked (see figure 2).
HIV/AIDS. Following its identification in 1983, the
spread of HIV intensified quickly. Despite progress in some regions,
HIV/AIDS shows no signs of abating globally (see figure 3).
Approximately 2.3 million people died from AIDS worldwide in 1998,
up dramatically from 0.7 million in 1993, and there were 5.8 million
new infections. According to WHO, some 33.4 million people were
living with HIV by 1998, up from 10 million in 1990, and the number
could approach 40 million by the end of 2000. Although infection and
death rates have slowed considerably in developed countries owing to
the growing use of preventive measures and costly new multidrug
treatment therapies, the pandemic continues to spread in much of the
developing world, where 95 percent of global infections and deaths
have occurred. Sub-Saharan Africa currently has the biggest regional
burden, but the disease is spreading quickly in India, Russia,
China, and much of the rest of Asia. HIV/AIDS probably will cause
more deaths than any other single infectious disease worldwide by
2020 and may account for up to one-half or more of infectious
disease deaths in the developing world alone.
A Word About Data
All data concerning global disease incidence, including WHO
data, should be treated as broadly indicative of trends rather than
accurate measures of disease prevalence. Much disease incidence in
developing countries, in particular, is either unreported or
under-reported due to a lack of adequate medical and administrative
personnel, the stigma associated with many diseases, or the
reluctance of countries to incur the trade, tourism, and other
losses that such revelations might produce. Since much morbidity and
mortality are multicausal, moreover, diagnosis and reporting of
diseases can vary and further distort comparisons. WHO and other
international entities are dependent on such data despite its
weaknesses and are often forced to extrapolate or build models based
on relatively small samples, as in the case of HIV/AIDS. Changes in
methodologies, moreover, can produce differing results. The ranking
of AIDS mortality ahead of TB mortality in figure 2, for example,
partly owes to the fact that HIV-positive individuals dying of TB
were included in the AIDS mortality category in the most recent WHO
survey.
TB. WHO declared TB a global emergency in 1993 and
the threat continues to grow, especially from multidrug resistant TB
(see figure 4). The disease is especially prevalent in Russia,
India, Southeast Asia, Sub-Saharan Africa, and parts of Latin
America. More than 1.5 million people died of TB in 1998, excluding
those infected with HIV/AIDS, and there were up to 7.4 million new
cases. Although the vast majority of TB infections and deaths occur
in developing regions, the disease also is encroaching into
developed regions due to increased immigration and travel and less
emphasis on prevention. Drug resistance is a growing problem; the
WHO has reported that up to 50 percent of people with multidrug
resistant TB may die of their infection despite treatment, which can
be 10 to 50 times more expensive than that used for drug-sensitive
TB. HIV/AIDS also has contributed to the resurgence of TB.
One-quarter of the increase in TB incidence involves co-infection
with HIV. TB probably will rank second only to HIV/AIDS as a cause
of infectious disease deaths by 2020.
Glossary
Infectious Disease
An illness due to a specific infectious agent that is spread from
an infected person, animal, or inanimate reservoir to a susceptible
host, either directly or indirectly, through an intermediate plant
or animal host, vector, or the inanimate environment.
Endemic
The constant presence of a disease or infectious agent within a
given geographic area.
Epidemic
The occurrence in an area of a disease or illness in excess of
what may be expected on the basis of past experience for a given
population (in the case of a new disease, such as AIDS, any
occurrence may be considered "epidemic").
Pandemic
A worldwide epidemic affecting an exceptionally high proportion
of the global population.
Prevalence
The number of existing cases of a disease among a total or
specified population in a given period of time; usually expressed as
a percent or as the number of cases per thousand, 10,000, and so
forth.
Malaria, a mainly tropical disease that seemed to
be coming under control in the 1960s and 1970s, is making a deadly
comeback--especially in Sub-Saharan Africa where infection rates
increased by 40 percent from 1970 to 1997 (see figure 5). Drug
resistance, historically a problem only with the most severe form of
the disease, is now increasingly reported in the milder variety,
while the prospects for an effective vaccine are poor. In 1998, an
estimated 300 million people were infected with malaria, and more
than 1.1 million died from the disease that year. Most of the deaths
occurred in Sub-Saharan Africa. According to the US Agency for
International Development (USAID), Sub-Saharan Africa alone is
likely to experience a 7- to 20-percent annual increase in
malaria-related deaths and severe illnesses over the next several
years.
Hepatitis B and C. Hepatitis B, which caused at
least 0.6 million deaths in 1997, is highly endemic in the
developing world, and some 350 million people worldwide are chronic
carriers (see figure 6). The less prevalent but far more lethal
hepatitis C identified in 1989 has grown dramatically and is a
significant contributor to cirrhosis and liver cancer. WHO estimated
that 3 percent of the global population was infected with the
hepatitis C virus by 1997 (see figure 7), which means that more than
170 million people were at risk of developing the diseases
associated with this virus. Various studies project that up to 25
percent of people with chronic hepatitis B and C will die of
cirrhosis of the liver and liver cancer over the next 20 to 30
years.
Lower respiratory infections, especially influenza
and pneumonia, killed 3.5 million people in 1998, most of them
children in developing countries, down from 4.1 million in 1993.
Owing to immunosuppression from malnutrition and growing microbial
resistance to commonly used drugs such as penicillin, these children
are especially vulnerable to such diseases and will continue to
experience high death rates.
Figure 2
Leading Infectious Disease Killers, 1998
Diarrheal diseases--mainly spread by contaminated
water or food--accounted for 2.2 million deaths in 1998, as compared
to 3 million in 1993, of which about 60 percent occurred among
children under five years of age in developing countries. The most
common cause of death related to diarrheal diseases is infection
with Escherichia coli. Other diarrheal diseases include
cholera, dysentery, and rotaviral diarrhea, prevalent throughout the
developing world and, more recently, in many former communist
states. Such waterborne and foodborne diseases will remain highly
prevalent in these regions in the absence of improvements in water
quality and sanitation.
Figure 3
Global HIV/AIDS Prevalence, 1998
Figure 4
Estimated TB Incidence, 1997
Figure 5
Malaria-Endemic Regions, 1997
Figure 6
Estimated Hepatitis B Prevalence, 1997
Measles. Despite substantial progress against
measles in recent years, the disease still infects some 42 million
children annually and killed about 0.9 million in 1998, down from
1.2 million in 1993. It is a leading cause of death among refugees
and internally displaced persons during complex humanitarian
emergencies. Measles will continue to pose a major threat in
developing countries (see figure 8), particularly Sub-Saharan
Africa, until the still relatively low vaccination rates are
substantially increased. It also will continue to cause periodic
epidemics in areas such as South America with higher, but still
inadequate, vaccination rates.
Factors Affecting Growth and Spread
With few exceptions, the resurgence of the infectious disease
threat is due as much to dramatic changes in human behavior and
broader social, economic, and technological developments as to
mutations in pathogens (see table 2). Changes in human behavior
include population dislocations, living styles, and sexual
practices; technology-driven medical procedures entailing some risks
of infection; and land use patterns. They also include rising
international travel and commerce that hasten the spread of
infectious diseases; inappropriate use of antibiotics that leads to
the development of microbial resistance; and the breakdown of public
health systems in some countries owing to war or economic decline.
In addition, climate changes enable diseases and vectors to expand
their range. Several of these factors interact, exacerbating the
spread of infectious diseases.
Table 2
Factors Contributing to Infectious Disease
Reemergence and Associated Diseases
|
| Contributing Factor(s) |
|
Associated Infectious Diseases |
| Human demographics and behavior |
|
Dengue/dengue hemorrhagic fever, sexually transmitted
diseases, giardiasis |
| Technology and industry |
|
Toxic shock syndrome, nosocomial (hospital-acquired)
infections, hemorrhagic colitis/hemolytic uremic syndrome
|
| Economic development and land use |
|
Lyme disease, malaria, plague, rabies, yellow fever,
Rift Valley fever, schistosomiasis |
| International travel and commerce |
|
Malaria, cholera, pneumococcal pneumonia |
| Microbial adaptation and change |
|
Influenza, HIV/AIDS, malaria, Staphylococcus aureus infections |
| Breakdown of public health measures |
|
Rabies, tuberculosis, trench fever, diphtheria, whooping
cough (pertussis), cholera |
| Climate change |
|
Malaria, dengue, cholera, yellow fever |
Source: Adapted from US Institute of Medicine, 1997.
Human Demographics and Behavior
Population growth and urbanization, particularly in the developing
world, will continue to facilitate the transfer of pathogens among
people and regions. Frequent and often sudden population movements
within and across borders caused by ethnic conflict, civil war, and
famine will continue to spread diseases rapidly in affected areas,
particularly among refugees. As of 1999, there were some 24 major
humanitarian emergencies worldwide involving at least 35 million
refugees and internally displaced people. Refugee camps, found
mainly in Sub-Saharan Africa and the Middle East, facilitate the
spread of TB, HIV, cholera, dysentery, and malaria. Well over 120
million people lived outside the country of their birth in 1998, and
millions more will emigrate annually, increasing the spread of
diseases globally. Behavioral patterns, such as unprotected sex with
multiple partners and intravenous drug use, will remain key factors
in the spread of HIV/AIDS.
Figure 7
Estimated Hepatitis C Prevalence, 1998
Figure 8
Reported Measles Incidence Rates, 1996
Technology, Medicine, and Industry
Although technological breakthroughs will greatly facilitate the
detection, diagnosis, and control of certain infectious and
noninfectious illnesses, they also will introduce new dangers,
especially in the developed world where they are used extensively.
Invasive medical procedures will result in a variety of
hospital-acquired infections, such as Staphylococcus aureus.
The globalization of the food supply means that nonhygienic food
production, preparation, and handling practices in originating
countries can introduce pathogens endangering foreign as well as
local populations. Disease outbreaks due to Cyclospora spp,
Escherichia coli, and Salmonella spp. in several
countries, along with the emergence, primarily in Britain, of Bovine
Spongiform Encephalopathy, or "mad cow" disease, and the related new
variant Creutzfeldt-Jakob disease (nvCJD) affecting humans, result
from such food practices.
Economic Development and Land Use
Changes in land and water use patterns will remain major factors in
the spread of infectious diseases. The emergence of Lyme disease in
the United States and Europe has been linked to reforestation and
increases in the deer tick population, which acts as a vector, while
conversion of grasslands to farming in Asia encourages the growth of
rodent populations carrying hemorrhagic fever and other viral
diseases. Human encroachment on tropical forests will bring
populations into closer proximity with insects and animals carrying
diseases such as leishmaniasis, malaria, and yellow fever, as well
as heretofore unknown and potentially dangerous diseases, as was the
case with HIV/AIDS. Close contact between humans and animals in the
context of farming will increase the incidence of zoonotic
diseases--those transmitted from animals to humans. Water management
efforts, such as dambuilding, will encourage the spread of
water-breeding vectors such as mosquitoes and snails that have
contributed to outbreaks of Rift Valley fever and schistosomiasis in
Africa.
International Travel and Commerce
The increase in international air travel, trade, and tourism will
dramatically increase the prospects that infectious disease
pathogens such as influenza--and vectors such as mosquitoes and
rodents--will spread quickly around the globe, often in less time
than the incubation period of most diseases. Earlier in the decade,
for example, a multidrug resistant strain of Streptococcus
pneumoniae originating in Spain spread throughout the world in a
matter of weeks, according to the director of WHO's infectious
disease division. The cross-border movement of some 2 million people
each day, including 1 million between developed and developing
countries each week, and surging global trade ensure that travel and
commerce will remain key factors in the spread of infectious
diseases.
Table 3
Examples of Drug-Resistant Infectious Agents and
Percentage of Infections That Are Drug Resistant,
by Country or Region
|
| Pathogen |
Drug |
Country/Region |
Percentage of Drug-Resistant Infections |
| Streptococcus pneumoniae |
Penicillin |
United States
Asia, Chile, Spain,
Hungary |
10 to 35
20
58 |
| Staphylococcus aureus |
Methicillin
Multidrug |
United States
Japan |
32
60 |
| Mycobacterium tuberculosis |
Any drug
Any drug
Multidrug |
United States
New York City
Eastern Europe |
13
16
20 |
| Plasmodium falciparum malaria |
Chloroquine
Mephloquine |
Kenya
Ghana
Zimbabwe
Burkina Faso
Thailand |
65
45
59
17
45 |
| Shigella dysenteride |
Multidrug |
Burundi, Rwanda |
100 |
Note: Antimicrobial resistance occurs when a disease-carrying
microbe (bacteria, virus, parasite, or fungus) is no longer affected
by a drug that previously was able to kill the microbe or prevent it
from growing. Even among populations of microorganisms that are
susceptible to a particular antimicrobial agent, at least a small
percentage of those organisms are naturally resistant, and their
proportion will grow as the others succumb to the antimicrobial
agent. Eventually this process renders the agent ineffective against
the microorganism.
Source: US Institute of Medicine, 1997; WHO, 1999.
Microbial Adaptation and Resistance
Infectious disease microbes are constantly evolving, oftentimes into
new strains that are increasingly resistant to available
antibiotics. As a result, an expanding number of strains of
diseases--such as TB, malaria, and pneumonia--will remain difficult
or virtually impossible to treat. At the same time, large-scale use
of antibiotics in both humans and livestock will continue to
encourage development of microbial resistance. The firstline drug
treatment for malaria is no longer effective in over 80 of the 92
countries where the disease is a major health problem. Penicillin
has substantially lost its effectiveness against several diseases,
such as pneumonia, meningitis, and gonorrhea, in many countries.
Eighty percent of Staphylococcus aureus isolates in the
United States, for example, are penicillin-resistant and 32 percent
are methicillin-resistant. A US Centers for Disease Control and
Prevention (USCDC) study found a 60-fold increase in high-level
resistance to penicillin among one group of Streptococcus
pneumoniae cases in the United States and significant resistance
to multidrug therapy as well. Influenza viruses, in particular, are
particularly efficient in their ability to survive and genetically
change, sometimes into deadly strains. HIV also displays a high rate
of genetic mutation that will present significant problems in the
development of an effective vaccine or new, affordable therapies.
Breakdown in Public Health Care
Alone or in combination, war and natural disasters, economic
collapse, and human complacency are causing a breakdown in health
care delivery and facilitating the emergence or reemergence of
infectious diseases. While Sub-Saharan Africa is the area currently
most affected by these factors, economic problems in Russia and
other former communist states are creating the context for a large
increase in infectious diseases. The deterioration of basic health
care services largely accounts for the reemergence of diphtheria and
other vaccine-preventable diseases, as well as TB, as funds for
vaccination, sanitation, and water purification have dried up. In
developed countries, past inroads against infectious diseases led to
a relaxation of preventive measures such as surveillance and
vaccination. Inadequate infection control practices in hospitals
will remain a major source of disease transmission in developing and
developed countries alike.
Climate Change
Climatic shifts are likely to enable some diseases and associated
vectors--particularly mosquito-borne diseases such as malaria,
yellow fever, and dengue--to spread to new areas. Warmer
temperatures and increased rainfall already have expanded the
geographic range of malaria to some highland areas in Sub-Saharan
Africa and Latin America and could add several million more cases in
developing country regions over the next two decades. The occurrence
of waterborne diseases associated with temperature-sensitive
environments, such as cholera, also is likely to increase.
Regional Trends and Response Capacity
The overall level of global health care capacity has improved
substantially in recent decades, but in most poorer countries the
availability of various types of health care--ranging from basic
pharmaceuticals and postnatal care to costly multidrug
therapies--remains very limited. Almost all research and development
funds allocated by developed country governments and pharmaceutical
companies, moreover, are focused on advancing therapies and drugs
relevant to developed country maladies, and those that are relevant
to developing country needs usually are beyond their financial
reach. This is generating a growing controversy between rich and
poorer nations over such issues as intellectual property rights, as
some developing countries seek to meet their pharmaceutical needs
with locally produced generic products. Malnutrition, poor
sanitation, and poor water quality in developing countries also will
continue to add to the disease burden that is overwhelming health
care infrastructures in many countries. So too, will political
instability and conflict and the reluctance of many governments to
confront issues such as the spread of HIV/AIDS. A global composite
measure of health care infrastructure devised by DIA's Armed Forces
Medical Intelligence Center (AFMIC) assesses factors such as the
priority attributed to health care, health expenditures, the quality
of health care delivery and access to drugs, and the extent of
surveillance and response systems. The AFMIC typology highlights the
disparities in health care capacity (see figure 9), as do various
WHO, UNAIDS, and World Bank studies.
Sub-Saharan Africa
Sub-Saharan Africa will remain the region most affected by the
global infectious disease phenomenon--accounting for nearly half of
infectious disease-caused deaths worldwide. Deaths from HIV/AIDS,
malaria, cholera, and several lesser known diseases exceed those in
all other regions. Sixty-five percent of all deaths in Sub-Saharan
Africa are caused by infectious diseases. Rudimentary health care
delivery and response systems, the unavailability or misuse of
drugs, the lack of funds, and the multiplicity of conflicts are
exacerbating the crisis. According to the AFMIC typology, with the
exception of southern Africa, most of Sub-Saharan Africa falls in
the lowest category. Investment in health care in the region is
minimal, less than 40 percent of the people in countries such as
Nigeria and the Democratic Republic of the Congo (DROC) have access
to basic medical care, and even in relatively well off South Africa,
only 50 to 70 percent have such access, with black populations at
the low end of the spectrum.
Figure 9
Typology of Countries by Health Care Status
Four-fifths of all HIV-related deaths and 70 percent of new
infections worldwide in 1998 occurred in the region, totaling 1.8-2
million and 4 million, respectively. Although only a tenth of the
world's population lives in the region, 11.5 million of 13.9 million
cumulative AIDS deaths have occurred there. Eastern and southern
African countries, including South Africa, are the worst affected,
with 10 to 26 percent of adults infected with the disease.
Sub-Saharan Africa has high TB prevalence, as well as the highest
HIV/TB co-infection rate, with TB deaths totaling 0.55 million in
1998. The hardest hit countries are in equatorial and especially
southern Africa. South Africa, in particular, is facing the biggest
increase in the region.
Sub-Saharan Africa accounts for an estimated 90 percent of the
global malaria burden (see figure 10). Ten percent of the regional
disease burden is attributed to malaria, with roughly 1 million
deaths in 1998. Cholera, dysentery, and other diarrheal diseases
also are major killers in the region, particularly among children,
refugees, and internally displaced populations. Forty percent of all
childhood deaths from diarrheal diseases occur in Sub-Saharan
Africa. The region also has a high rate of hepatitis B and C
infections and is the only region with a perennial meningococcal
meningitis problem in a "meningitis belt" stretching from west to
east. Sub-Saharan Africa also suffers from yellow fever, while
trypanasomiasis or "sleeping sickness" is making a comeback in the
DROC and Sudan, and the Marburg virus also appeared in DROC for the
first time in 1998. Ebola hemorrhagic fever strikes sporadically in
countries such as the DROC, Gabon, Cote d'Ivoire, and Sudan (see
figure 11).
Asia and the Pacific
Although the more developed countries of Asia and the Pacific, such
as Japan, South Korea, Australia, and New Zealand, have strong
records in combating infectious diseases, infectious disease
prevalence in South and Southeast Asia is almost as high as in
Sub-Saharan Africa. The health care delivery system of the Asia and
Pacific region--the majority of which is privately financed--is
particularly vulnerable to economic downturns even though this is
offset to some degree by much of the region's reliance on
traditional medicine from local practitioners. According to the
AFMIC typology, 90 to 100 percent of the populations in the most
developed countries, such as Japan and Australia, have access to
high-quality health care. Forty to 50 percent have such access among
the large populations of China and South Asia, while southeast Asian
health care is more varied, with less than 40 percent enjoying such
access in Burma and Cambodia, and 50 to 70 percent in Thailand,
Malaysia, and the Philippines. In South and Southeast Asia,
reemergent diseases such as TB, malaria, cholera, and dengue fever
are rampant, while HIV/AIDS, after a late start, is growing faster
than in any other region.
TB caused 1 million deaths in the Asia and Pacific region in
1998, more than any other single disease, with India and China
accounting for two-thirds of the total. Several million new cases
occur annually--most in India, China and Indonesia--representing as
much as 40 percent of the global TB burden. HIV/AIDS is increasing
dramatically, especially in India, which leads the world in absolute
numbers of HIV/AIDS infections, estimated at 3-5 million. China is
better off than most of the countries to its south, but it too has a
growing AIDS problem, with HIV infections variously estimated at
0.1-0.4 million and spreading rapidly. Regionwide, the number of
people infected with HIV could overtake Sub-Saharan Africa in
absolute numbers before 2010.
Figure 10
Malaria Mortality Annual Rates Since 1900
There were 19.5 million new malaria infections estimated in the
Asia and Pacific region in 1998, many of them drug resistant, and
100,000 deaths due to malaria. Acute respiratory infections, such as
pneumonia, cause about 1.8 million childhood deaths annually--over
half of them in India--while dengue (including dengue hemorrhagic
fever/dengue shock syndrome) outbreaks have spread throughout the
region in the last five years. Waterborne illnesses such as
dysentery and cholera also take a heavy toll in poor and crowded
areas. Asian, particularly Chinese, agricultural practices place
farm animals, fowl, and humans in close proximity and have long
facilitated the emergence of new strains of influenza that cause
global pandemics. Hepatitis B is widely prevalent in the region,
while hepatitis C is prevalent in China and in parts of southeast
Asia. In 1999 the newly recognized Nipah virus spread throughout pig
populations in Malaysia, causing more than 100 human deaths there
and a smaller number in nearby Singapore.
Figure 11
Health care workers take a rest during the outbreak of Ebola
hemorrhagic fever in Zaire, now the Democratic Republic of the
Congo, in 1995, Eighty percent of those who become ill died.
Latin America
Latin American countries are making considerable progress in
infectious disease control, including the eradication of polio and
major reductions in the incidence and death rates of measles,
neonatal tetanus, some diarrheal diseases, and acute respiratory
infections. Nonetheless, infectious diseases are still a major cause
of illness and death in the region, and the risk of new and
reemerging diseases remains substantial. Widening income
disparities, periodic economic shocks, and rampant urbanization have
disrupted disease control efforts and contributed to widespread
reemergence of cholera, malaria, TB, and dengue, especially in the
poorer Central American and Caribbean countries and in the Amazon
basin of South America. According to the AFMIC typology, Latin
America's health care capacity is substantially more advanced than
that of Sub-Saharan Africa and somewhat better than mainland Asia's,
with 70 to 90 percent of populations having access to basic health
care in Chile, Costa Rica, and Cuba on the upper end of the scale.
Less than 50 percent have such access in Haiti, most of Central
America, and the Amazon basin countries, including the rural
populations in Brazil.
Cholera reemerged with a vengeance in the region in 1991 for the
first time in a century with 400,000 new cases, and while dropping
to 100,000 cases in 1997, it still comprises two-thirds of the
global cholera burden. TB is a growing problem regionwide,
especially in Brazil, Peru, Argentina, and the Dominican Republic
where drug-resistant cases also are on the rise. Haiti does not
provide data but probably also has a high infection rate. HIV/AIDS
also is spreading rapidly, placing Latin America third behind
Sub-Saharan Africa and Asia in HIV prevalence. Prevalence is high in
Brazil and especially in the Caribbean countries (except Cuba),
where 2 percent of the population is infected. Malaria is prevalent
in the Amazon basin. Dengue reemerged in the region in 1976, and
outbreaks have taken place in the last few years in most Caribbean
countries and parts of South America. Hepatitis B and C prevalence
is greatest in the Amazon basin, Bolivia, and Central America, while
dengue hemorhagic fever is particularly prevalent in Brazil,
Colombia, and Venezuela. Yellow fever has made a comeback over the
last decade throughout the Amazon basin, and there have been several
recent outbreaks of gastrointestinal disease attributed to E. coli
infection in Chile and Argentina. Hemorrhagic fevers are present in
almost all South American countries, and most hantavirus pulmonary
syndrome occurs in the southern cone.
Middle East and North Africa
The region's conservative social mores, climatic factors, and high
levels of health spending in oil-producing states tend to limit some
globally prevalent diseases, such as HIV/AIDS and malaria, but
others, such as TB and hepatitis B and C, are more prevalent. The
region's advantages are partially offset by the impact of
war-related uprooting of populations, overcrowded cities with poor
refrigeration and sanitation systems, and a dearth of water,
especially clean drinking water. Health care capacity varies
considerably within the region, according to the AFMIC typology.
Israel and the Arabian Peninsula states minus Yemen are in far
better shape than Iraq, Iran, Syria, and most of North Africa.
Ninety to 100 percent of the Israeli population and 70 to 90 percent
of the Saudi population have good access to health care. Elsewhere,
access ranges from less than 40 percent in Yemen to 50 to 70 percent
in the smaller Gulf states, Jordan and Tunisia, while most North
African states fall into the 40- to 50-percent category.
The HIV/AIDS impact is far lower than in other regions, with
210,000 cases, or 0.13 percent of the population, including 19,000
new cases, in 1998. This owes in part to above-average
underreporting because of the stigma associated with the disease in
Muslim societies and the authoritarian nature of most governments in
the region. TB, including multidrug resistant varieties, is more
problematic, especially in Iran, Iraq, Yemen, Libya, and Morocco,
with an estimated 140,000 deaths in 1998. Malaria is significant
only in Iran, Iraq, and Yemen, but diarrheal and childhood diseases
caused 0.3 million deaths each in 1998. Other prominent or
reemerging diseases in the region include all types of hepatitis,
with Egypt reporting the highest prevalence worldwide of the C
variety. Brucellosis now infects some 90,000 people; leishmaniasis
and sandfly fever also are endemic in the region; and various
hemorrhagic fevers occur, as well.
The Former Soviet Union and Eastern Europe
The sharp decline in health care infrastructure in Russia and
elsewhere in the former Soviet Union (FSU) and, to a lesser extent,
in Eastern Europe--owing to economic difficulties--are causing a
dramatic rise in infectious disease incidence. Death rates
attributed to infectious diseases in the FSU increased 50 percent
from 1990 to 1996, with TB accounting for a substantial number of
such deaths. According to the AFMIC typology, access to health care
ranges from 50 to 70 percent in most European FSU states, including
Russia and Ukraine, and from 40 to 50 percent in FSU states located
in Central Asia. This is generally supported by WHO estimates
indicating that only 50 to 80 percent of FSU citizens had regular
access to essential drugs in 1997, as compared to more than 95
percent a decade earlier as health care budgets and
government-provided health services were slashed. Access to health
care is generally better in Eastern Europe, particularly in more
developed states such as Poland, the Czech Republic, and Hungary,
where it ranges from 70 to 90 percent, while only 50 to 70 percent
have access in countries such as Bulgaria and Romania. More than 95
percent of the population throughout the East European region had
such access in 1987, according to WHO.
Crowded living conditions are among the causes fueling a TB
epidemic in the FSU, especially among prison populations--while
surging intravenous drug use and rampant prostitution are
substantially responsible for a marked increase in HIV/AIDS
incidence. There were 111,000 new TB infections in Russia alone in
1996, a growing number of them multidrug resistant, and nearly
25,000 deaths due to TB--numbers that could increase significantly
following periodic releases of prisoners to relieve overcrowding.
The number of new infections for the entire FSU in 1996 was 188,000,
while East European cases totaled 54,000. More recent data indicate
that the TB infection rate in Russia more than tripled from 1990 to
1998, with 122,000 new cases reported in 1998 and the total number
of cases expected to reach 1 million by 2002. After a slow and late
start, HIV/AIDS is spreading rapidly throughout the European part of
the FSU beyond the original cohort of intravenous drug users, though
it is not yet reflected in official government reporting. An
estimated 270,000 people were HIV-positive in 1998, up more than
five-fold from 1997. Although Ukraine has been hardest hit, Russia,
Belarus, and Moldova have registered major increases. Various senior
Russian Health Ministry officials predict that the HIV-positive
population in Russia alone could reach 1 million by the end of 2000
and could reach 2 million by 2002. East European countries will fare
better as renewed economic growth facilitates recovery of their
health care systems and better enables them to expand preventive and
treatment programs.
Diphtheria reached epidemic proportions in the FSU in the first
half of the decade, owing to lapses in vaccination. Reported annual
case totals grew from 600 cases in 1989 to more than 40,000 in 1994
in Russia, with another 50,000 to 60,000 in the rest of the FSU.
Cholera and dysentery outbreaks are occurring with increasing
frequency in Russian cities, such as St. Petersburg and Moscow, and
elsewhere in the FSU, such as in T'bilisi, owing to deteriorating
water treatment and sewerage systems. Hepatitis B and C, spread
primarily by intravenous drug use and blood transfusions, are on the
rise, especially in the non-European part of the FSU. Polio also has
reappeared owing to interruptions in vaccination, with 140 new cases
in Russia in 1995.
Western Europe
Western Europe faces threats from a number of emerging and
reemerging infectious diseases such as HIV/AIDS, TB, and hepatitis B
and C, as well as several zoonotic diseases. Its status as a hub of
international travel, commerce, and immigration, moreover,
dramatically increases the risks of importing new diseases from
other regions. Tens of millions of West Europeans travel to
developing countries annually, increasing the prospects for the
importation of dangerous diseases, as demonstrated by the
importation of typhoid in 1999. Some 88 percent of regional
population growth in the first half of the decade was due to
immigration; legal immigrants now comprise about 6 percent of the
population, and illegal newcomers number an estimated 6 million.
Nonetheless, the region's highly developed health care
infrastructure and delivery system tend to limit the incidence and
especially the death rates of most infectious diseases, though not
the economic costs. Access to high-quality care is available
throughout most of the region, although governments are beginning to
limit some heretofore generous health benefits, and a growing
antivaccination movement in parts of Western Europe, such as
Germany, is causing a rise in measles and other vaccine-preventable
diseases. The AFMIC typology gives somewhat higher marks to northern
over some southern European countries, but the region as a whole is
ranked in the highest category, along with North America.
After increasing sharply for most of the 1980s and 1990s, HIV
infections, and particularly HIV/AIDS deaths, have slowed
considerably owing to behavioral changes among high-risk populations
and the availability and funding for multidrug treatment. Some 0.5
million people were living with HIV/AIDS in 1998, down slightly from
510,000 the preceding year, and there were 30,000 new cases and
12,000 deaths, with prevalence somewhat higher in much of southern
Europe than in the north. TB, especially its multidrug resistant
strains, is on the upswing, as is co-infection with HIV,
particularly in the larger countries, with some 50,000 TB cases
reported in 1996. Hepatitis C prevalence is growing, especially in
southern Europe. Western Europe also continues to suffer from
several zoonotic diseases, among which is the deadly new variant
Creutzfeldt-Jakob disease (nvCJD), linked to the bovine spongiform
encephalopathy or "mad cow disease" outbreak in the United Kingdom
in 1995 that has since ebbed following implementation of strict
control measures. Other recent disease concerns include
meningococcal meningitis outbreaks in the Benelux countries and
leishmaniasis-HIV co-infection, especially in southern Europe.
International Response Capacity
International organizations such as WHO and the World Bank,
institutions in several developed countries such as the US CDC, and
Nongovernmental Organizations (NGOs) will continue to play an
important role in strengthening both international and national
surveillance and response systems for infectious diseases.
Nonetheless, progress is likely to be slow, and development of an
integrated global surveillance and response system probably is at
least a decade or more away. This owes to the magnitude of the
challenge; inadequate coordination at the international level; and
lack of funds, capacity, and, in some cases, cooperation and
commitment at the national level. Some countries hide or understate
their infectious disease problems for reasons of international
prestige and fear of economic losses. Total international
health-related aid to low- and middle-income countries--some $2-3
billion annually--remains a fraction of the $250 billion health bill
of these countries.
WHO
WHO has the broadest health mandate under the UN system, including
establishing health priorities, coordinating global health
surveillance, and emergency assistance in the event of disease
outbreaks. Health experts give WHO credit for major successes, such
as the eradication of smallpox, near eradication of polio, and
substantial progress in controlling childhood diseases, and in
facilitating the expansion of primary health care in developing
countries. It also has come under criticism for becoming top heavy,
unfocused in its mission, and overly optimistic in its health
projections. WHO defenders blame continued member state parsimony
that has kept WHO's regular biennial budget to roughly $850 million
for several years and forced it to rely more on voluntary
contributions that often come with strings attached as the cause of
its shortcomings.
The election last year of Gro Harlem Bruntland as Secretary
General, along with a series of reforms, including expansion of the
Emerging and other Communicable Diseases Surveillance and Control
(EMC) Division, has placed WHO in a better position to revitalize
itself. Internal oversight and transparency have been expanded,
programs and budgets are undergoing closer scrutiny, and management
accountability is looming larger. Bruntland has moved quickly to
streamline upper-level management and has installed new top
managers, mostly from outside the organization, including from the
private sector. She also is working to strengthen country offices
and to make the regional offices more responsive to central
direction. WHO is increasing its focus on the fight against
resurgent malaria, while a better-funded EMC is expanding efforts to
establish a global surveillance and response system in cooperation
with UNAIDS, UNICEF, and national entities such as the US CDC, the
US DoD, and France's Pasteur Institute.
Other UN Agencies Involved in Health Care
WHO competes for resources with the many other UN agencies
that are increasingly involved in health care. The United Nations
Children's Fund (UNICEF) focuses on children's health. The United
Nations AIDS Program (UNAIDS) focuses on improving the response
capacity toward HIV/AIDS at the country, regional, and global levels
in cooperation with WHO and other UN agencies. Other UN agencies
involved in health care issues include the UN Development Program (UNDP);
the UN Family Planning Agency (UNFPA); the UN High Commissioner for
Refugees (UNHCR); the UN Educational, Scientific and Cultural
Organization (UNESCO); the International Labor Organization (ILO);
the Food and Agricultural Organization (FAO); and the World Food
Program (WFP).
The World Bank
The growing sense that health is linked inexorably to socioeconomic
development, has prompted the World Bank to expand its health
activities. According to a 1997 study by the US Institute of
Medicine, the most significant change in the global health arena
over the past decade has been the growth in both financial and
intellectual influence of the World Bank, whose health loans have
grown to $2.5 billion annually, including $800 million for
infectious diseases. Health experts generally welcome the Bank's
greater involvement in the health sector, viewing it as efficient
and responsive in areas such as health sector financial reform. Some
remain concerned that the Bank's emphasis on fiscal balance can
sometimes have a negative health and social impact in developing
countries. Some developing countries resent what they perceive as
the domination of Bank decisionmaking and priority setting by the
richer countries.
Nongovernmental Organizations
Another major change in the global health arena over the last decade
is the increasingly important role of NGOs, which provide direct
assistance, including emergency shelter and aid, as well as
long-term domestic health care delivery. NGOs also build community
awareness and support for WHO and other international and bilateral
surveillance and response efforts. At the same time, health experts
note that NGOs, like their governmental counterparts, are driven in
part by their own self interests, which sometimes conflict with
those of host and donor governments.
Bilateral Assistance
The United States, through USAID, the CDC, the National Institutes
for Health (NIH), and the Defense Department's overseas
laboratories, is a major contributor to international efforts to
combat infectious diseases. It is joined increasingly by other
developed nations and regional groupings, such as the European Union
(EU), that provide assistance bilaterally, as well as through
international organizations and NGOs. The Field Epidemiology
Training Programs--run jointly by the CDC and WHO--as well as the EU-US
Task Force on Emerging Diseases and the US-Japan Common Scientific
Agenda, are key examples of developed-country programs focusing on
infectious diseases.
National Limitations
A major obstacle to effective global surveillance and control of
infectious diseases will continue to be poor or inaccurate national
health statistical reporting by many developing countries and lack
of both capacity and will to properly direct aid (see figure 12) and
to follow WHO and other recommended health care practices. Those
areas of the world most susceptible to infectious disease problems
are least able to develop and maintain the sophisticated and costly
communications equipment needed for effective disease surveillance
and reporting. In addition to the barriers dictated by low levels of
development, revealing an outbreak of a dreaded disease may harm
national prestige, commerce, and tourism. For example, nearly every
country initially denied or minimized the extent of the HIV/AIDS
virus within its borders, and even today, some countries known to
have significant rates of HIV infection refuse to cooperate with
WHO, which can only publish the information submitted by surveying
nations. Only a few, such as Uganda, Senegal, and Thailand, have
launched major preventative efforts, while many WHO members do not
even endorse AIDS education in schools. Similarly, some countries
routinely and falsely deny the existence of cholera within their
borders.
Figure 12
Inadequate Commitment to Infectious Disease Control Policies at
Country Level
Aid programs to prevent and treat infectious diseases in
developing countries depend largely on indigenous health workers for
their success and cannot be fielded effectively in their absence.
Educational programs aimed at preventing disease exposure frequently
depend on higher literacy levels and assume cultural and social
factors that often are absent.
Alternative Scenarios and Outlook for Infectious Diseases
The impact of infectious diseases over the next 20 years will be
heavily influenced by three sets of variables. The first is the
relationship between increasing microbial resistance and scientific
efforts to develop new antibiotics and vaccines. The second is the
trajectory of developing and transitional economies, especially
concerning the basic quality of life of the poorest groups in these
countries. The third is the degree of success of global and national
efforts to create effective systems of surveillance and response.
The interplay of these drivers will determine the overall outlook.
On the positive side, reduced fertility and the aging of the
population, continued economic development, and improved health care
capacity in many countries, especially the more developed, will
increase the progress toward a health transition by
2020 whereby the impact of infectious diseases ebbs, as compared to
noninfectious diseases. On the negative side, continued rapid
population growth, urbanization, and persistent poverty in much of
the developing world, and the paradox in which some aspects of
socioeconomic development--such as increased trade and
travel--actually foster the spread of infectious diseases, could
slow or derail that transition. So, too, will growing microbial
resistance among resurgent diseases, such as malaria and TB, and the
proliferation or intensification of new ones, such as HIV/AIDS.
Two scenarios--one optimistic and one pessimistic--reflect
differences in the international health community concerning the
global outlook for infectious diseases. We present and critically
assess these scenarios, elaborate on the pessimistic scenario, and
develop a third, combining some elements of each, that we judge as
more likely to prevail over the period of this Estimate.
The Optimistic Scenario: Steady Progress
According to a key 1996 World Bank/WHO study cited earlier that
articulated the optimistic scenario, a health transition--resulting
from key drivers, such as aging populations, socio-economic
development, and medical advances--already is under way in developed
countries and also in much of Asia and Latin America that is likely
to produce a dramatic reduction in the infectious disease threat.
The study projects that deaths caused primarily by infectious
diseases will fall steadily from 34 percent of the total disease
burden in 1990 to 15 percent in 2020. Those from noninfectious
diseases are likely to climb from 55 percent of the total disease
burden to 73 percent, with the remainder of deaths due to accidents
and other types of injuries. According to the study's ranking of
major disease threats over this 30-year time frame, noninfectious
diseases generally will rise in importance, led by heart disease and
mental illness, as will accidental injuries. TB will remain in 7th
place in 2020, and HIV/AIDS will move from 28th place to 10th, with
the two combined accounting for more than 90 percent of infectious
disease-caused deaths among adults, almost all of them in developing
countries. Lower respiratory infections will fall from the top spot
to sixth place, however, while measles and malaria will drop
precipitously from 8th and 11th place to 24th and 25th, respectively
(see figures 13 and 14).
Toward a Global Surveillance and Response System
Although a formal, fully integrated surveillance and response
system does not yet exist at the global level, the WHO's Emerging
and other Communicable Diseases Surveillance and Control (EMC)
Division, working with UNAIDS and more than 200 collaborating
centers and laboratories, is making some progress.
- Independent networks of laboratories monitoring specific
diseases and the microbial resistance phenomenon are being
expanded or established, while networks for reporting and
exchanging information about infectious disease outbreaks are
being enhanced. These networks include one on influenza
encompassing more than 100 worldwide laboratories; a network for
HIV/AIDS and other sexually transmitted diseases; several new or
smaller networks focusing on hepatitis C and yellow fever; and
one on microbial resistance in general. The EMC has taken the
lead in revising international health reporting requirements to
encompass a broader array of diseases.
- Member states' capacities to monitor infectious diseases
are being enhanced by increasing the number of developing
country health professionals capable of monitoring and
responding to disease outbreaks.
- Global infectious disease control efforts are being
improved by better assisting countries to deal with disease
outbreaks, such as ensuring that trained experts, vaccines, and
therapeutics are available to deal with such outbreaks.
- The global exchange of information among and within
surveillance networks is being improved by expanding the
availability of equipment for electronic communication through
the Internet and World Wide Web sites, such as PROMED.
Aging Populations. Demographic changes are one key
to this scenario, which projects that declining fertility and infant
mortality, along with increased life expectancy, will result in an
aging global population more apt to be felled by noninfectious
diseases and by accidental injury than by infectious diseases, which
tend to occur among the very young. While these trends are generally
evident on a global scale, there is considerable variance by region
and level of development. Fertility has been cut by a half over the
last 50 years in most regions of the world, infant mortality
worldwide dropped from 129 to 60 per 1,000 live births from 1960 to
1996, and life expectancy worldwide increased from 50 to 64 years,
according to the 1998 UN Human Development Report. The overall
population growth rate, meanwhile, will slow to 1.2 percent annually
by 2015, as compared to 1.7 percent between 1970 and 1995.
Socioeconomic Progress. Under this scenario,
continued improved access to safe food and water in developing
countries, better nutrition, and improved literacy will sharply
reduce infant and adult mortality, already cut by more than half in
developing countries since 1965. The number of people with an
average per capita caloric intake of 2,700 per day is projected to
increase from 1.8 billion in 1990-92 to 2.7 billion by 2010--or
roughly 50 percent--and adult literacy in the least developed
countries is expected to grow from 49 percent in 1995 to 61 percent
in 2010. All of these factors would thus produce better health and
health practices for young and old alike.
Economic Gains. The optimistic scenario assumes
that worldwide economic growth and rising incomes will further
reduce poverty and provide funding for improvements in health care
infrastructure, though it will be uneven in scope and by region.
Real per capita income levels from 1970 to 1995, for example,
increased by 200 percent in east Asia, 60 percent in south Asia, and
25 to 50 percent in Latin America.
Improved Health Care Capacity. Improvements in
health care delivery in accordance with WHO's "health for all" goal
are projected to continue in such areas as prenatal care for women,
contraception, childhood and adult immunization, and availability of
essential drugs. Already more than 90 percent of women in developed
and transitional countries and 50 percent in the least developed
countries receive some prenatal care. The number of women in
developing countries using contraceptives increased from 9 percent
in 1965 to 60 percent in 1998. Immunization rates against six common
vaccine-preventable diseases have increased from 5 percent to 80
percent of the relevant population over the last two decades.
Table 4
Projected Change in the Rank Order of Global
Disease Burden for Leading Causes, Worldwide
1990-2020, According to the Optimistic Scenarioa
|
1990
Rank Order |
Disease or Injury |
2020
Rank Order |
| 1 |
Lower respiratory infections |
6 |
| 2 |
Diarrheal diseases |
9 |
| 3 |
Conditions arising during perinatal period |
11 |
| 4 |
Unipolar major depression |
2 |
| 5 |
Ischemic heart disease |
1 |
| 6 |
Cerebrovascular disease |
4 |
| 7 |
Tuberculosis |
7 |
| 8 |
Measles |
25 |
| 9 |
Road traffic deaths |
3 |
| 10 |
Congenital abnormalities |
13 |
| 11 |
Malaria |
24 |
| 12 |
Chronic obstructive pulmonary disease |
5 |
| 13 |
Falls |
19 |
| 14 |
Iron-deficiency anemia |
39 |
| 15 |
Protein-energy malnutrition |
37 |
| 16 |
War |
8 |
| 17 |
Self-inflicted injuries |
14 |
| 19 |
Violence |
12 |
| 28 |
HIV |
10 |
| 33 |
Trachea, bronchus, and lung cancers |
15 |
a Of the six infectious diseases ranked in 1990, only
lower respiratory infections, diarrheal diseases, and measles are
trending downward as projected, while malaria is increasing and
tuberculosis and HIV are growing far faster than projected.
Nonetheless, more pessimistic experts have not developed an
alternative model and generally adopt the projections of the Murray
and Lopez model.
Source: Adapted from World Bank, WHO, 1996, edited by Christopher
J. L. Murray and Alan D. Lopez.
And access to drugs continues to expand, except in the former
communist states in Eastern Europe and in the former Soviet Union.
All of these factors will combine to reduce childhood diseases and
mortality.
Medical Advances. The optimistic scenario also
notes that several diseases are on the verge of elimination or close
to it, such as polio, neonatal tetanus, and leprosy, while measles
incidence also will be reduced dramatically as vaccination rates
increase in the least developed countries. Research efforts are
projected to result in the development of more effective, safer, and
in some cases, less expensive vaccines. Disease agents against which
vaccines have been developed recently include Lyme disease, while
several others--such as for malaria, dengue fever, and Ebola--are in
various stages of development. As the human genetic code is
deciphered, additional genes that influence infectious disease risk
are likely to be discovered.
Scenario Assessment. Our overall judgment is that
the "steady progress" scenario is very unlikely to transpire over
the time period of this Estimate. Although the scenario captures
some real trends, it overstates the progress achievable, while
underestimating the risks.
- The global life expectancy increases projected by the
optimists are likely to be substantially offset by HIV/AIDS and
related diseases, such as TB, which are already causing a major
reduction in life expectancy in the most heavily affected
Sub-Saharan African countries and will be spreading extensively
throughout heavily populated Asia during the time period of the
Estimate. Optimists acknowledge that HIV/AIDS and TB will be the
overarching infectious disease threats by 2020, but they
understate the magnitude of that threat, while their projections
of a steep decline in malaria deaths is belied by the disease's
resurgence and growing death toll.
- The picture of steady socioeconomic progress is not
consistent with the most recent surveys of conditions in
developing countries undertaken by the United Nations, the World
Bank, and other international agencies. These studies point to a
slowing of progress in basic social indicators in much of the
developing world, even before the recent global financial
crisis.
- Although we judge that economic growth is likely to
continue, we are less confident that the dramatic reductions in
poverty achieved in many countries in the last generation will
be sustained. Growth is likely to be halting in many countries,
owing to structural economic problems and the impact of
recurring developing world economic crises.
- The rapidly expanding costs of many drugs, especially those
that attack critical infectious diseases, such as HIV/AIDS and
multidrug resistant TB and malaria, threaten to limit the
sustainability of improved health care. Furthermore, despite
economic growth, pressures on government budgets, especially
from rising pension and other costs, may limit the prospects for
increased health financing.
- The optimists may place too much emphasis on the steady
progress of science, which is inconsistent with the demonstrated
difficulty of developing new drugs and vaccines for complex
pathogens such as HIV and malaria.
Figure 13
Projected Changes in the Global Distribution of Deaths and DALYS by
Causes According to the Optimistic Scenario, 1990-2020
Figure 14
Various Projected HIV/AID Death Rates Per 1,000 People, by Region,
1990-2020
The Pessimistic Scenario: Progress Stymied
Surprisingly, even the most pessimistic epidemiologists have done
little to project the long-term implications of their analysis and
simply adopt the longer term projections of the World Bank/WHO model
in the absence of a worst case model. We have developed a worst case
scenario culled from a variety of epidemiological and broader health
studies. This scenario highlights the dangers posed by microbial
resistance among reemergent diseases such as TB and malaria. It
takes a more concerned view of new diseases and of the HIV/AIDS
pandemic, in particular, and is skeptical about the adequacy of
world health care capacity to confront these challenges. It
emphasizes continuing and difficult-to-address poverty challenges in
developing countries and projects an incomplete health
transition that prolongs the heavy infectious disease burden
in the least developed countries and sustains their role as
reservoirs of infection for the rest of the world.
A Not-So-Benign Demographic Picture. Although the
global population growth rate is slowing, world population still
will expand by 80 million annually through 2015, mostly in
developing countries, where especially the youngest population
cohorts will remain highly susceptible to infectious diseases.
Infant mortality in the least developed countries is running at
nearly double the global average and is eight times that of
developed countries, while life expectancy is 23 years below that of
developed countries and 13 years below the global average. These
trends will be especially evident in urban areas where poverty,
overcrowding, poor sanitation, and polluted drinking water create
conditions in which infectious diseases and relevant vectors, such
as mosquitoes and rodents, thrive. The problem will only worsen when
the number of people living in cities exceeding 10 million more than
doubles to 450 million by 2015, with almost all of the increase
occurring in developing world cities.
Disparate Socioeconomic Development. Although the
broad long-term trend in global economic growth is likely to be
upward, this scenario posits a growing prosperity gap between the
developed and developing countries and within developing countries,
particularly the poorest cohort. Despite the near doubling of real
per capita income from 1970 to 1995 globally, for example, it
declined in Sub-Saharan Africa, and income gaps within these
countries are widening substantially, as well. One-fifth of
developing country populations remain malnourished--the biggest risk
factor for infectious diseases--3 billion lack adequate sanitation,
and 1 billion still have no access to safe drinking water. Recurring
economic crises in developing countries, moreover, are likely to
have a negative impact on foreign and domestic investor willingness
to invest in them, slowing their economic growth rates further and
widening the gap with developed countries.
Inadequate Health Care Delivery and Disease Surveillance.
Tightening of health care eligibility requirements, privatization,
and the growing costs of health care, particularly for HIV/AIDS
patients, are likely to continue to squeeze health care delivery
worldwide, but the impact will be greatest in Sub-Saharan Africa as
well as in China--where 80 percent of the rural population no longer
has subsidized health care--and in the former communist states.
Under this scenario access to essential drugs and basic medical care
in these regions will remain poor or deteriorate, and many
Sub-Saharan African countries, in particular, will continue to rely
on international and NGO assistance for a modicum of health care and
surveillance capability. Although current global surveillance and
response capabilities are likely to improve, the emergence of an
integrated global network is at least a decade or more away, owing
to inadequate capacity and cooperation and resource constraints.
Toward a Postantibiotic Era? The growth and
intensity of antimicrobial resistance among infectious pathogens
increases, due both to pathogen mutation and to inappropriate and
indiscriminate use of therapeutic drugs in both developed and
developing countries. Two-thirds of all oral antibiotics worldwide
are obtained without a prescription and are inappropriately used
against diseases such as TB, malaria, pneumonia, and more routine
childhood infections. These practices contribute to antimicrobial
resistance and the severe, nearly impossible to treat
hospital-acquired infections. Even vancomycin, the last defense
against a number of such infections, is losing effectiveness.
According to WHO, "In the struggle for supremacy, the microbes are
sprinting ahead and the gap between their ability to mutate into
resistant strains and man's ability to counter them is widening
fast." Some epidemiologists and health experts have even suggested
that we may be entering a postantibiotic era in which existing
antimicrobials, in general, will lose their effectiveness against
the most common infectious diseases.
Inadequate Drug and Vaccine Development. The
development of new antimicrobial drugs and vaccines does not keep
pace with new and resistant pathogens owing to the complexity of
pathogens such as HIV and malaria, the slow pace of new
antimicrobial development and approval, and in many cases a lack of
commercial incentives for drug companies to develop new antibiotics
for diseases prevalent in developing countries. Most recent efforts
to develop new or more effective drugs and vaccines against dengue,
malaria, E. coli, TB, and several other infectious diseases
are likely to be prolonged. WHO estimates that development of an
effective vaccine against malaria, for example, is at least seven to
15 years away, while a cure for HIV/AIDS is likely to be even more
distant. The majority of new drugs and vaccines, moreover, are
likely to be beyond the reach of most developing country populations
because of their cost.
Continued Threat From HIV/AIDS. The threat from
HIV/AIDS and related diseases over the next two decades continues to
surge. Although behavioral changes and multidrug treatments will
slow infection and death rates in developed countries, these
advances are likely to be more than offset by the rapid spread of
the disease among the vast populations of India, Russia, China, and
Latin America. HIV/AIDS burden projections since the start of the
pandemic have consistently been surpassed, while the slow pace of
behavioral changes in the developing world, high costs of available
treatment, and the obstacles to developing a cure portend more
increases in the future. The 1996 joint World Bank/WHO model's
projections that HIV/AIDS deaths would peak in 2006 with 1.7 million
deaths, for example, were already exceeded by the 2.3 million deaths
in1998. Two other models likewise have underestimated the HIV/AIDS
threat, albeit less so. Similarly, the World Bank/WHO model's
baseline projection of roughly 2.2 million TB deaths in 2020 is
likely to be exceeded in the next decade, as may its worst case
scenario of 3.2 million deaths if HIV co-infection surges. According
to UNAIDS epidemiologists, Asia alone is likely to outstrip
Sub-Saharan Africa in the absolute number of HIV carriers by 2010.
When coupled with the poor prospects for developing a cure and
likely growing resistance to the multidrug therapies now in use, the
HIV/AIDS burden could reach catastrophic proportions over the next
20 years (see figure 14).
The "Infectiousness" of Noninfectious Diseases.
Prospects that the infectious disease threat may not diminish, as
compared to noncommunicable diseases, are further butressed by the
growing body of evidence that infectious pathogens cause or
contribute to many diseases--such as diabetes, cancer, heart
disease, and ulcers--previously thought to be caused by
environmental or lifestyle factors. WHO and other institutions
estimate that up to 15 percent of cancers, for example, could be
avoided by preventing the infectious diseases associated with them,
including more than 50 percent of stomach and cervical cancers and
80 percent of liver cancers.
Scenario Assessment. Our overall judgment is that
the "progress stymied" scenario, while more plausible than the
optimistic scenario, is also unlikely to develop over the period of
this Estimate. Although the pessimistic scenario provides an
important counterpoint to the assumptions in the "steady progress"
scenario, it understates the likely longer term impact of economic
development, scientific progress, and political pressures in
responding to the infectious disease threat.
- The demographic projections understate the likely impact of
continued progress in reducing infant mortality.
- Improvements in the economic conditions of poor countries
and the poorest within countries are probably more important for
the infectious disease outlook than the widening "prosperity
gap" both between countries and within countries. Although the
outlook for Sub-Saharan Africa remains bleak, for the rest of
the world progress against infectious diseases would stall only
under the most dire global economic scenario.
- The negative impact on health care delivery of privatization
and the transitions in former communist states is likely to be
most heavily felt in the immediate future. Free market reforms
eventually will improve health care delivery.
- The current success of the "mutating microbes" in the race
against scientific innovation will, in and of itself, call forth
a greater research effort that will, over time, increase the
likelihood of a reversal of this trend.
- The rapid spread of HIV/AIDS in developing and former
communist countries is likely to reinvigorate international
efforts to address the virus through both medical and behavioral
approaches. It will especially give impetus to the search for a
more cost-effective approach than at present.
- While growth in surveillance and response capabilities are
slow, they are real and are unlikely to be reversed.
The Most Likely Scenario: Deterioration, Then Limited
Improvement
According to this scenario, continued deterioration during the first
half of our time frame--led by hard core killers such as HIV/AIDS,
TB, and malaria--is followed by limited improvement in the second
half, owing primarily to gains against childhood and
vaccine-preventable diseases such as diarrheal diseases, neonatal
tetanus, and measles. The scale and scope of the overall infectious
disease threat diminishes, but the remaining threat consists of
especially deadly or incurable diseases such as HIV/AIDS, TB,
hepatitis C and possibly, heretofore, unknown diseases, with
HIV/AIDS and TB likely comprising the overwhelming majority of
infectious disease deaths in developing countries alone by 2020.
Scenario Assessment
Because some elements of both the optimistic and pessimistic
scenarios cited above are likely to appear during the 20-year time
frame of this Estimate, we are likely to witness neither steady
progress against the infectious disease threat nor its unabated
intensification. Instead, progress is likely to be slow and uneven,
with advances, such as the recent development of a new type of
antibiotic drug against certain hospital-acquired infections,
frequently offset by renewed setbacks, such as new signs of growing
microbial resistance among available HIV/AIDS drugs and withdrawal
of a promising new vaccine against rotavirus because of adverse side
effects. On balance, negative drivers, such as microbial resistance,
are likely to prevail over the next decade, but given time, positive
ones, such as gradual socioeconomic development and improved health
care capacity, will likely come to the fore in the second decade.
- The negative trends cited in the pessimistic scenario above,
such as persistent poverty in much of the developing world,
growing microbial resistance and a dearth of new replacement
drugs, inadequate disease surveillance and control capacity, and
the high prevalence and continued spread of major killers such
as HIV/AIDS, TB, and malaria, are likely to remain ascendant and
worsen the overall problem during the first half of our time
frame.
- Sub-Saharan Africa, India, and Southeast Asia will remain
the hardest hit by these diseases. The European FSU states and
China are likely to experience a surge in HIV/AIDS and related
diseases such as TB. The developed countries will be threatened
principally by the real possibility of a resurgence of the
HIV/AIDS threat owing to growing microbial resistance to the
current spectrum of multidrug therapies and to a wide array of
other drugs used to combat infectious diseases.
The broadly positive trends cited in the more optimistic
scenario, such as aging populations, global socioeconomic
development, improved health care capacity, and medical advances,
are likely to come to the fore during the second half of our time
frame in all but the least developed countries, and even the least
developed will experience a measure of improvement.
- Aging populations and expected continued declines in
fertility throughout Asia, Latin America, the former FSU states,
and Sub-Saharan Africa will sharply reduce the size of age
cohorts that are particularly susceptible to infectious diseases
owing to environmental or behavioral factors.
- Socioeconomic development, however fitful, and resulting
improvements in water quality, sanitation, nutrition, and
education in most developing countries will enable the most
susceptible population cohorts to better withstand infectious
diseases both physically and behaviorally.
- The worsening infectious disease threat we posit for the
first decade of our time frame is likely to further energize the
international community and most countries to devote more
attention and resources to improved infectious disease
surveillance, response, and control capacity. The WHO's new
campaign against malaria, recent developed country consideration
of tying debt forgiveness for the poorest countries in part to
their undertaking stronger commitments to combat disease,
self-initiated efforts by Sub-Saharan African governments to
confront HIV/AIDS, and greater pharmaceutical industry
willingness to provide more drugs to poor countries at
affordable prices are likely to be harbingers of more such
efforts as the infectious disease threat becomes more acute.
- The likely eventual approval of new drugs and vaccines--now
in the developmental stage--for major killers such as dengue,
diarrheal diseases, and possibly even malaria will further ease
the infectious disease burden and help counter the microbial
resistance phenomenon.
Together, these developments are likely to set the stage for at
least a limited improvement in infectious disease control,
particularly against childhood and vaccine-preventable diseases,
such as respiratory infections, diarrheal diseases, neonatal
tetanus, and measles in most developing and former communist
countries. Given time--and barring the appearance of a deadly and
highly infectious new disease, a catastrophic expansion of the
HIV/AIDS pandemic, or the release of a highly contagious biological
agent capable of rapid and widescale secondary spread--such medical
advances, behavioral changes, and improving national and
international surveillance and response capacities will eventually
produce substantial gains against the overall infectious disease
threat. In the event that HIV/AIDS takes a catastrophic turn for the
worse in both developed and developing countries, even the authors
of the optimistic World Bank/WHO model concur that all bets are off.
Economic, Social, and Political Impacts
The persistent infectious disease burden is likely to aggravate
and, in extreme cases, may even provoke social fragmentation,
economic decay, and political polarization in the hardest hit
countries in the developing and former communist worlds in
particular, especially in the worst case scenario outlined above.
This, in turn, will hamper progress against infectious diseases.
Even under the most likely scenario that posits some attenuation of
the infectious disease threat in the second half of our time frame,
new and reemergent infectious diseases are likely to have a
disruptive impact on global economic, social, and political
dynamics.
Economic Impact Likely To Grow Macroeconomic Impact
The macroeconomic costs of the infectious disease burden are
increasingly significant for the most seriously affected countries
despite the partially offsetting impact of declines in population
growth, and they will take an even greater toll on productivity,
profitability, and foreign investment in the future. A senior World
Bank official considers AIDS to be the single biggest threat to
economic development in Sub-Saharan Africa. A growing number of
studies suggest that AIDS and malaria alone will reduce GDP in
several Sub-Saharan African countries by 20 percent or more by 2010.
- The impact of infectious diseases on annual GDP growth in
heavily affected countries already amounts to as much as a
1-percentage point reduction in the case of HIV/AIDS on average
and 1 to 2 percentage points for malaria, according to World
Bank studies. A recent Namibian study concluded that AIDS cost
the country nearly 8 percent of GDP in 1996, while a study of
Kenya projected that GDP will be 14.5 percent smaller in 2005
than it otherwise would have been without the cumulative impact
of AIDS. The annual cost of malaria to Kenya's GDP was estimated
at 2 to 6 percent and at 1 to 5 percent for Nigeria.
Microeconomic Impact
The impact of infectious diseases--especially HIV/AIDS--at the
sector and firm level already appears to be substantial and growing
and will be reflected eventually in higher GDP losses (see figure
15), especially in the more advanced developing countries with
specialized work force needs.
- A recent study by the Zimbabwe Commercial Farmers' Union
estimated that production losses due to HIV/AIDS in the communal
and resettlement areas--the African farm-holder sector--is close
to 50 percent.
- WHO estimates that small farmers in Nigeria and Kenya spend
13 and 5 percent, respectively, of total household income on
malaria treatment that would otherwise go to other forms of
consumption of more benefit to the economy.
Although a 1996 World Bank-sponsored study of nearly 1,000 firms
in four African countries focusing solely on the impact of
AIDS-related employee turnover concluded that it was not likely to
substantially affect firm profits, several individual firms and
their AIDS consultants paint a much bleaker picture by 1999. Using
broader measures of AIDS-related costs, such as absenteeism,
productivity declines, health and insurance payments, and
recruitment and training, they projected profits to drop by 6 to 8
percent or more and productivity to decline by 5 percent. They are
especially troubled by the high rate of loss of middle- and
upper-level managers to AIDS and the dearth of replacements, as well
as the loss of large numbers of skilled workers to AIDS in the
mining and other key sectors. According to one expert, South African
companies will begin to feel the full impact of the AIDS epidemic by
2005. One study of the projected impact of AIDS on employee benefit
costs in South Africa concludes that benefit costs would nearly
triple to 19 percent of salaries from 1995 to 2005, substantially
eroding corporate profits.
Figure 15
Projected Impact of AIDS on GDP of Selected Countries in Sub-Saharan
Africa
Infectious Disease-Related Trade Disruptions
Infectious diseases will continue to cause costly periodic
disruptions in trade and commerce in every region of the world.
- Avian flu in Hong Kong. The avian influenza
outbreak in 1997 cost the former colony hundreds of millions of
dollars in lost poultry production, commerce, and tourism, with
airport arrivals in November of that year alone down by 22
percent from the preceding year.
- BSE and nvCJD in Britain. The outbreak of
BSE and new variant Creutzfeldt-Jakob disease in the United
Kingdom in 1995 prompted a mass slaughter of cattle, drastically
cut beef consumption, and led to the imposition of a three-year
EU embargo against British beef. The losses to the British
economy were estimated by the WHO at $5.75 billion, including $2
billion in lost beef exports.
- Cyclospora in Guatemalan raspberries. The
outbreak of cyclospora-related illness in the United States and
Canada associated with raspberries from Guatemala led to curbs
in imports that cost Guatemala several million dollars in lost
revenue.
- Cholera in Peru. The outbreak of cholera in
1991 cost the Peruvian fishing industry an estimated $775
million in lost tourism and trade because of a temporary ban on
seafood exports.
- Foot and mouth disease in Taiwan. In 1997
an outbreak of foot and mouth disease (FMD) devastated Taiwan's
pork industry--one of the largest in the world--shutting down
exports for a full year.
- Nipah in Malaysia. In 1999, the Nipah virus
caused the shutdown of over half of the country's pig farms and
an embargo against pork exports.
- Plague in India. The plague outbreak in
Surat, India, in 1994 and ensuing panic sparked a sudden exodus
of 0.5 million people from the region and led to abrupt
shutdowns of entire industries, including aviation, and tourism,
as several countries froze trade, banned travel from India, and
sent some Indian migrants home. The WHO estimated the outbreak
cost India some $2 billion.
Fiscal Impact. Infectious diseases will increase
pressure on national health bills that already consume some 7 to 14
percent of GDP in developed countries, up to 5 percent in the better
off developing countries, but currently less than 2 percent in least
developed states.
- By 2000, the cumulative direct and indirect costs of AIDS
alone are likely to have topped $500 billion, according to
estimates by the Global AIDS Policy Coalition at Harvard
University. In Latin America, the Pan-American Health
Organization in 1994 estimated it would take a decade and $200
billion to bring the cholera pandemic in the region under
control through a massive water cleanup effort, or nearly 80
percent of total developing country health spending for that
year. The direct costs of fighting malaria in Sub-Saharan Africa
increased from $800 million in 1989 to $2.2 billion in 1997,
largely owing to the far higher cost of treating the growing
number of drug-resistant cases, and the trend toward higher
costs is likely to continue.
AIDS, along with TB and malaria--particularly the drug-resistant
varieties--makes large budgetary claims on national health systems'
resources (see figure 16). Policy choices will continue to be
required along at least three dimensions: spending for health versus
spending for other objectives; spending more on prevention in order
to spend less on treatment; and treating burgeoning AIDS-infected
populations versus treating other illnesses.
- Although prevention is cost-efficient--the eradication of
smallpox has shaved $20 billion off the global health bill, and
polio eradication would save as much as $3 billion annually by
2015--most countries will not be able to afford even basic care
for those infected with diseases such as TB and HIV/AIDS. In
Zimbabwe, for example, more than half the meager health budget
is spent on treating AIDS. Yet, treating one AIDS patient for a
year in Sub-Saharan Africa costs as much as educating 10 primary
school students for one year.
- Public health spending on AIDS and related diseases
threatens to crowd out other types of health care and social
spending. In India, for example, simulated annual government
health expenditures in the context of a severe AIDS epidemic in
which total expenditures, including AIDS costs, are subsidized
at 21 percent would add $2 billion annually to the government's
health bill through 2010 and $5 billion with a government
subsidy of 51 percent. In Kenya, HIV/AIDS treatment costs are
projected to account for 50 percent of health spending by 2005.
In South Africa, such costs could account for 35 to 84 percent
of public health expenditures by 2005, according to one
projection.
- Even given the budgetary dominance of AIDS, care is likely
to be limited to the most basic of therapies. Few countries will
be able to afford the high cost of multidrug treatment for
HIV/AIDS--or for drug-resistant TB and malaria--ensuring that
such diseases will continue to be highly prevalent. Only about 1
percent of HIV/AIDS patients even in relatively well off South
Africa currently undergo multidrug treatment, for example, while
it would cost Russia several billion dollars annually to provide
such treatment for its surging HIV/AIDS case load--which is
unlikely given its fiscal difficulties. In addition to the cost
of the drugs, few countries can afford to build and maintain the
health care infrastructure that makes effective treatment
possible.
Figure 16
Potential AIDS Treatment Costs in Selected Countries in Sub-Saharan
Africa
Disruptive Social Impact
At least some of the hardest-hit countries, initially in Sub-Saharan
Africa and later in other regions, will face a demographic
catastrophe as HIV/AIDS and associated diseases reduce human life
expectancy dramatically and kill up to a quarter of their
populations over the period of this Estimate (see table 5). This
will further impoverish the poor and often the middle class and
produce a huge and impoverished orphan cohort unable to cope and
vulnerable to exploitation and radicalization.
Life Expectancy and Population Growth. Until the
early 1990s, economic development and improved health care had
raised the life expectancy in developing countries to 64 years, with
prospects that it would go higher still. The growing number of
deaths from new and reemergent diseases such as AIDS, however, will
slow or reverse this trend toward longer life spans in heavily
affected countries by as much as 30 years or more by 2010, according
to the US Census Bureau. For example, life expectancy will be
reduced by 30 years in Botswana and Zimbabwe, by 20 years in Nigeria
and South Africa, by 13 years in Honduras, by eight years in Brazil,
by four years in Haiti, and by three years in Thailand.
Family Structure. The degradation of nuclear and
extended families across all classes will produce severe social and
economic dislocations with political consequences, as well. Nearly
35 million children in 27 countries will have lost one or both
parents to AIDS by 2000; by 2010, this number will increase to 41.6
million. Nineteen of the hardest hit countries are in Sub-Saharan
Africa, where HIV/AIDS has been prevalent across all social sectors.
Children are increasingly acquiring HIV from their mothers during
pregnancy or through breast-feeding, ensuring prolongation and
intensification of the epidemic and its economic reverberations.
With as much as a third of the children under 15 in hardest-hit
countries expected to comprise a "lost orphaned generation" by 2010
with little hope of educational or employment opportunities, these
countries will be at risk of further economic decay, increased
crime, and political instability as such young people become
radicalized or are exploited by various political groups for their
own ends; the pervasive child soldier phenomenon may be one example.
Destabilizing Political and Security Impact
In our view, the infectious disease burden will add to political
instability and slow democratic development in Sub-Saharan Africa,
parts of Asia, and the former Soviet Union, while also increasing
political tensions in and among some developed countries.
- The severe social and economic impact of infectious
diseases, particularly HIV/AIDS, and the infiltration of these
diseases into the ruling political and military elites and
middle classes of developing countries are likely to intensify
the struggle for political power to control scarce state
resources. This will hamper the development of a civil society
and other underpinnings of democracy and will increase pressure
on democratic transitions in regions such as the FSU and
Sub-Saharan Africa where the infectious disease burden will add
to economic misery and political polarization.
- A study by Ted Robert Gurr, et al., on the causes of state
instability in 127 cases over a 40-year period ending in 1996
suggests that infant mortality is a good indicator of the
overall quality of life, which correlates strongly with
political instability. According to the research, three
variables out of 75--high infant mortality--which in developing
countries owes substantially to infectious diseases; low
openness to trade; and incomplete democratization accounted for
two-thirds of demonstrated instability. The study defined
"instability" as revolutionary wars, ethnic wars, genocides, and
disruptive regime transitions. High infant mortality has a
particularly strong correlation with the likelihood of state
failure in partial democracies.
Table 5
Projected Demographic Indicators for 2010 in Selected
Countries
With and Without AIDS
|
| Country |
Projected Child Mortality Per 1,000 Live
Births, 2010 |
|
Projected Life Expectancy, 2010 |
| |
With AIDS |
Without |
|
With AIDS |
Without |
| Sub-Saharan Africa |
| Botswana |
120 |
38 |
|
38 |
66 |
| Burkina Faso |
145 |
109 |
|
46 |
61 |
| Burundi |
129 |
91 |
|
45 |
61 |
| Cameroon |
108 |
78 |
|
50 |
63 |
| Cote d'Ivoire |
121 |
84 |
|
47 |
62 |
| Dem. Rep. of Congo |
116 |
97 |
|
52 |
60 |
| Ethiopia |
183 |
137 |
|
39 |
55 |
| Kenya |
105 |
45 |
|
44 |
69 |
| Lesotho |
122 |
71 |
|
45 |
66 |
| Malawi |
203 |
136 |
|
35 |
57 |
| Namibia |
119 |
38 |
|
39 |
70 |
| Nigeria |
113 |
68 |
|
46 |
65 |
| Rwanda |
166 |
106 |
|
38 |
59 |
| South Africa |
100 |
49 |
|
48 |
68 |
| Swaziland |
152 |
78 |
|
37 |
63 |
| Tanzania |
131 |
96 |
|
46 |
61 |
| Uganda |
121 |
92 |
|
48 |
60 |
| Zambia |
161 |
97 |
|
38 |
60 |
| Zimbabwe |
116 |
32 |
|
39 |
70 |
| Latin America |
| Brazil |
31 |
21 |
|
68 |
76 |
| Haiti |
129 |
119 |
|
54 |
59 |
| Honduras |
55 |
29 |
|
60 |
73 |
| Southeast Asia |
| Burma |
80 |
70 |
|
59 |
63 |
| Cambodia |
134 |
124 |
|
53 |
57 |
| Thailand |
25 |
21 |
|
73 |
75 |
aProbable deaths before age 5.
Source: Adapted from United States Bureau of the Census, 1998.
Infectious diseases also will affect national security and
international peacekeeping efforts as militaries and military
recruitment pools experience increased deaths and disabilities from
infectious diseases. The greatest impact will be among
hard-to-replace officers, noncommissioned officers, and enlisted
soldiers with specialized skills and among militaries with advanced
weapons and weapons platforms of all kinds.
- HIV/AIDS prevalence in selected militaries, mostly in
Sub-Saharan Africa, generally ranges from 10 to 60 percent (see
table 6). This is considerably higher than their civilian
populations and owes to risky lifestyles and deployment away
from home. Commencement of testing and exclusion of HIV-positive
recruits in the militaries of a few countries, is reducing HIV
prevalence but it continues to grow in most militaries.
- Militaries in key FSU states are increasingly experiencing
the impact of negative health developments within their
countries, such as deteriorating health infrastructure and
reduced funding. One in three Russian draftees currently is
rejected for various health reasons, as compared to one in 20 in
1985, according to one Russian newspaper report.
- Mounting infectious disease-caused deaths among the military
officer corps in military-dominated and democratizing polities
also may contribute to the deprivation, insecurity, and
political machinations that incline some to launch coups and
counter-coups aimed, more often than not, at plundering state
coffers.
It is difficult to make a direct connection between high HIV/AIDS
and other infectious disease prevalence in military forces and
performance in battle. But, given that a large number of officers
and other key personnel are dying or becoming disabled, combat
readiness and capability of such military forces is bound to
deteriorate.
- Infectious disease-related deaths and disabilities are
likely to have the greatest impact on the capabilities of
Sub-Saharan militaries, particularly those that have achieved at
least a modest level of modernization in weapons systems and
platforms. Over the longer term, the consequences of the
continuing spread of deadly diseases such as HIV/AIDS on the
capabilities of the more modernized militaries in FSU states and
possibly China and certain rogue states with large armies and
modern weapons arsenals may be severe as well.
The negative impact of high infectious disease prevalence on
national militaries also is likely to be felt in international and
regional peacekeeping operations, limiting their effectiveness and
also making them vectors for the further spread of diseases among
coalition peacekeepers and local populations.
- Although the United Nations officially requires that
prospective peacekeeping troops be "disease free," it is
difficult to enforce this rule with such methods as HIV testing,
given the paucity of available troops and the potential
noncompliance of many contributing states.
- Healthy peacekeeping forces will remain at risk of being
infected by disease-carrying forces and local populations, as
well as by high-risk behavior and inadequate medical care.
In developed countries, the political debate over AIDS and other
infectious diseases is likely to focus on budgetary issues and
negligence in the handling of blood and foodstuffs, as well as on
treatment of infectious diseases.
- HIV blood and other controversies in several European
countries have sparked political uproars and led to the
dismissal or prosecution of government officials, and have even
contributed to the fall of some governments.
Table 6
HIV Prevalence in Selected Militaries in
Sub-Saharan Africa
|
| Country |
Estimated HIV
Prevalence
(percent) |
| Angola |
40 to 60 |
| Congo (Brazzaville) |
10 to 25 |
| Cote d'Ivoire |
10 to 20 |
| Democratic Republic of the Congo |
40 to 60 |
| Eritrea |
10 |
| Nigeria |
10 to 20 |
| Tanzania |
15 to 30 |
Source: DIA/AFMIC, 1999.
Infectious diseases also will loom larger in global interstate
relations as related embargoes and boycotts to prevent their spread
create trade frictions and controversy over culpability, such as in
the recently ended three-year EU embargo of British beef, which was
imposed to stop the spread of mad cow disease. Developed countries,
moreover, will come under pressure from international and
nongovernmental organizations, as well as from developing countries,
to deal with infectious disease-related instability and economic and
medical needs in the hardest-hit countries. A growing controversy,
in this regard, will be over drug-related intellectual property
rights, in which developing countries will press for more and
cheaper drugs from developed country pharmaceutical firms and resort
to producing their own generic brands if they are rebuffed. States
will remain concerned, as well, about the growing biological warfare
threat from rogue states and terrorist groups.
Infectious Diseases and US National Security
As a major hub of global travel, immigration, and commerce, along
with having a large civilian and military presence and wide-ranging
interests overseas, the United States will remain at risk from
global infectious disease outbreaks, or even a bioterrorist incident
using infectious disease microbes. Infectious diseases will continue
to kill nearly 170,000 Americans annually and many more in the event
of an epidemic of influenza or yet-unknown disease or a steep
decline in the effectiveness of available HIV/AIDS drugs. Although
several emerging infectious diseases, such as HIV/AIDS, were first
identified in the United States, most, including HIV/AIDS, originate
outside US borders, with the entry of the West Nile virus in 1999 a
case in point (see inset).
Threats to the US Civilian Population
The US civilian population will remain directly vulnerable to a wide
variety of infectious diseases, from resurgent ones such as
multidrug resistant TB to deadly newer ones such as HIV/AIDS and
hepatitis C. Infectious disease-related deaths in the United States
have increased by about 4.8 percent per year since 1980 to 59 deaths
per 100,000 people by 1996, or roughly 170,000 deaths annually, as
compared to an annual decrease of 2.3 percent in the preceding 15
years and an alltime low of 36 deaths per 100,000 in 1980 (see
figure 17). The USCDC estimates that the total direct and indirect
medical costs from infectious diseases comprise some 15 percent of
all US health care expenditures or $120 billion in 1995 dollars.
In the opinion of the US Institute of Medicine, the next major
infectious disease threat to the United States may be, like HIV, a
previously unrecognized pathogen. Barring that, the most likely
known infectious diseases to directly and significantly impact the
United States over the next decade will be HIV/AIDS, hepatitis C,
and multidrug resistant TB, or a new, more lethal variant of
influenza. Foodborne illnesses and hospital-acquired infections also
pose a threat:
- HIV/AIDS was first identified in the United
States in 1983 but originated in Sub-Saharan Africa. In the
United States, HIV/AIDS deaths surged from 7,000 in 1985 to
50,000 in 1995 before dropping dramatically to 17,000 in 1997 as
a result of behavioral and therapeutic changes among the most at
risk populations. The total number of those infected reached
890,000 for all of North America in 1998, including 44,000 new
infections, most of them in the United States. Although
HIV/AIDS-related death rates have declined sharply, the poor
prospects that a vaccine will be available over the next decade
or more, along with the likelihood that the virus will develop
growing resistance to the protease-inhibitor drugs now in use,
portend a continued rise in the infection rate and a renewed
rise in the death rate.
- Hepatitis C. Some 4 million Americans are
chronic carriers of hepatitis C, which was first identified in
the United States in 1989. The hepatitis C burden will continue
to grow for at least another decade due to the disease's long
incubation period, with the number of deaths possibly surpassing
HIV/AIDS deaths by 2005 even though the rate of new infections
is dropping, owing to improved blood supply testing. About 15
percent of those infected will develop life-threatening
cirrhosis of the liver, and many more will experience a more
slowly developing chronic liver disease, including cancer. The
disease also will remain the leading cause of liver
transplantation.
- Foodborne illnesses. According to the USCDC,
tens of millions of foodborne illness cases, including 9,000
deaths, occur each year in the United States. The threat from
foodborne illnesses will persist given changing consumption
patterns and further globalization of the food supply.
- The threat from highly virulent,
antimicrobial-resistant pathogens such as
Staphylococcus aureus, Streptococcus pneumoniae, and
enterrococci--which kill some 14,000 hospital patients
annually--is likely to grow, particularly if the remaining small
arsenal of effective drugs, such as vancomycin, becomes
ineffective.
- TB. After declining dramatically for several
decades, TB in the first half of the 1990s made a comeback in
urban areas and in some 13 states with large refugee and
immigrant populations, where some 23,000 to 27,000 cases were
reported annually, up from a low of 22,000 in 1984. More
alarming was the rise of multidrug resistant TB from 10 percent
of total cases before 1984 to 52 percent of cases resistant to
at least one drug and 32 percent resistant to two or more of the
five frontline anti-TB drugs a decade later. Some high-risk
populations in prisons and those with HIV/AIDS have experienced
death rates from TB as high as 70 to 90 percent. Although a
massive and costly intervention by state and local authorities
reversed the overall infection rate to 18,000 by 1998, the
multidrug resistant TB threat persists, and TB incidence
continues to grow among immigrant populations. About 40 percent
of all active TB cases in the United States--up from 16 percent
in 1982--currently occur among immigrants, particularly illegal
ones from countries where TB is highly endemic.
- Influenza. Although the deadly 1918 influenza
pandemic that caused more than 0.5 million US deaths appears to
have started in the United States, almost all others have
originated in China and Southeast Asia. Epidemiologists
generally agree that the threat of another "killer" influenza
pandemic is high and that it is not a question of whether, but
when, it will occur. Even in the absence of a widespread
"killer" pandemic, influenza has caused 30,000 US deaths
annually in recent years--nearly double the annual average in
the 1972-84 period, owing in part to the high vulnerability to
the disease of the growing cohort of older Americans and
HIV-infected persons. Influenza will remain essentially an
uncontrolled disease because the viruses are highly efficient in
their ability to survive and change into more virulent strains.
USCDC researchers predict that, in an influenza epidemic
infecting 15 percent of the US population, the mean number of
expected deaths would be approximately 97,000 in one year,
regardless of immunization status. The number of
hospitalizations would total 314,000, and the number of
outpatient cases would reach 18 million. If the attack rate were
35 percent, the number of expected deaths would be 227,000 in
one year and all other illness rates would be correspondingly
higher.
Other Infectious Disease Threats
Other diseases that are periodically imported and are more likely to
be costly in economic terms rather than in lives lost include
malaria, cholera, and various animal diseases:
- Malaria. Malaria was domestically eliminated
in the 1960s but has reemerged over the last two decades due to
the increase in immigration and international travel. Currently,
some 1,200 cases of malaria are reported to the USCDC annually,
with about half occurring among US travelers to highly endemic
countries in the tropics and the other half among foreign
nationals entering the United States, primarily agricultural
workers and illegal migrants. Although malaria outbreaks have
been relatively isolated and have been brought under control
quickly, the disease has the potential to become reestablished
in the United States because of the abundance of mosquito
vectors, especially in southern states.
- Fears that cholera, which has become endemic
in Latin America over the past decade, would find its way into
the United States have not been realized, but isolated cases
have been occurring at a more frequent rate than at any time
since 1962 when cholera surveillance commenced. Thus, the
disease looms as a potential threat.
- Dengue. Dengue, along with the far more
serious dengue hemorrhagic fever and dengue shock syndrome, was
reintroduced into the United States in the mid-1980s by foreign
travelers; the mosquito vector is now widespread throughout the
southeast. There were 90 cases in 1998, all of which were
acquired overseas.
- Foreign animal diseases. In addition to the
more obvious human impacts, imported animal diseases present
considerable potential risks to the domestic economy, trade, and
commerce. Those potentially capable of significantly harming US
agriculture include foot and mouth disease (FMD),
avian influenza, bovine spongiform encephalopathy,
and African swine fever. An outbreak of foot and mouth
disease in the US livestock industry could cost as much as $20
billion over 15 years in increased consumer costs, reduced
livestock productivity, and restricted trade, according to USDA
estimates. Another USDA study revealed that, if African swine
fever were to become reestablished in the US swine population,
the cost over a 10-year period would be $5.4 billion.
Mechanisms of Disease Entry Into the United States
The following are a few prominent methods of pathogen entry
into the United States:
- International travel. More than 57 million
Americans traveled outside the United States for recreational
and business purposes in 1998--often to high risk
countries--more than double the number just a decade before. In
addition, tens of millions of foreign-born travelers enter the
United States every year. Travelers on commercial flights can
reach most US cities from any part of the world within 36
hours--which is shorter than the incubation periods of many
infectious diseases.
- Immigration. Approximately 1 million
immigrants and refugees enter the United States legally each
year, often from countries with high infectious disease
prevalence, while several hundred thousand enter illegally. The
USCDC has the authority to detain, isolate, or provisionally
release persons at US ports of entry showing symptoms of any one
of seven diseases (yellow fever, cholera, diphtheria, infectious
TB, plague, suspected smallpox, and viral hemorrhagic fevers).
Although each individual must undergo a medical examination
before entering the country, potentially excludable conditions
may be in the incubating and therefore less detectable stages.
- Moreover, US law prohibits the Immigration and
Naturalization Service from returning refugees who have credible
reasons to fear political persecution, including those refugees
afflicted with infectious diseases.
- Returning US military forces. Although US
military populations are immunized against many infectious
diseases and are especially sensitized to detecting any symptoms
before or after their return to the United States, not all cases
are likely to be detected, especially among National Guardsmen
and Reservists, who are far more likely to enter the civilian
health care system and may not associate a later-developing
illness with their overseas travel.
- The globalization of food supplies.
Foodborne illnesses have become more common as the number of
food imports has doubled over the past five years, owing to
changing consumer preferences and increased trade. At certain
times of the year, more than 75 percent of the fruits and
vegetables available in grocery stores and restaurants are
imported and, therefore, potentially more likely to be infected
with pathogenic microorganisms, according to a foodborne disease
expert.
Figure 17
Trends in Infectious Disease-Related Mortality Rates in the United
States
Threats to Deployed Military Forces
Deployed US military forces have historically experienced higher
rates of hospital admission from infectious diseases than from
battlefield combat and noncombat injuries (see figure 18 and table
7). In addition to disease transmission between deployed troops and
indigenous populations, warfare-related social disruption often
creates refugees and internally displaced persons that can pass
infections along to US military forces. Allied coalition forces may
themselves bring infectious diseases into an area for the first time
and transmit them to US forces and the indigenous population.
Threats to deployed US forces will vary by country, region, and
the nature of the deployment and its mission:
- Least threatened will be US forces deployed in longstanding
US, NATO, and other allied bases in Europe, especially northern
Europe, and in Japan, where base medical facilities, food
sources and handling, as well as local health care
infrastructures are on a par with US standards.
- At highest risk will be those forces deployed to less
developed regions for contingency operations such as
humanitarian, peacekeeping, and peace enforcement missions.
Local medical care in such regions often is poor, and infectious
disease prevalence is high, both among the local population and
sometimes among coalition peacekeeping forces.
- Specific examples of diseases that have and may continue to
appear in association with military and peacekeeping operations
include respiratory diseases such as TB and influenza, diarrheal
diseases, malaria, hepatitis A and E, sexually transmitted
diseases, dengue and dengue hemorrhagic fever, and leishmaniasis.
Figure 18
US Army Hospital Admissions During War
Impact on US Interests Abroad
In addition to their impact on the US population, infectious
diseases will add to the social, economic, and political strains in
key regions and countries in which the United States has significant
interests or may be called upon to provide assistance:
- Infectious diseases are likely to slow socioeconomic
development in developing and former communist countries and
regions of interest to the United States. This will challenge
democratic development and transitions and possibly contribute
to humanitarian emergencies and military conflicts to which the
United States may need to respond.
- Infectious disease-related trade embargoes and restrictions
on travel and immigration also will cause frictions among and
with key trading partners and other selected states.
Table 7
Disease Threats to US Forces in the Gulf
|
| Disease Category |
|
Examples
|
|
Endemic Levels a
|
| Diarrheal |
|
Bacterial, protozoal, viral |
|
Moderately-to-highly endemic |
| Other foodborne or waterborne |
|
Hepatitis A and E, typhoid/paratyphoid fevers |
|
Moderately-to-highly endemic |
| Vectorborne |
|
Malaria
Sandfly fever, Leishmaniasis, other arboviral (including dengue, West
Nile, Sindbis, Crimean-Congo hemorrhagic fevers) |
|
Focally endemic in Oman, Saudi Arabia, UAE Endemic
|
| Person-to-person/close contact |
|
Tuberculosis, meningococcal meningitis |
|
Low-to-moderately endemic |
| Sexually transmitted and/or
bloodborne contact |
|
Hepatitis B/D and C, Gonorrhea |
|
Moderately-to-highly endemic |
| Other endemic |
|
Brucellosis, Q fever, leptospirosis, trachoma,
intestinal parasites, anthrax |
|
Endemic, especially in lower socioeconomic groups
|
a Usual level of disease occurrence in an area.
Source: DIA/AFMIC, 1997.
The Biological Warfare Threat
The biological warfare and terrorism threat to US national security
is on the rise as rogue states and terrorist groups also exploit the
ease of global travel and communication in pursuit of their goals:
- The ability of such foreign-based groups and individuals to
enter and operate within the United States has already been
demonstrated and could recur. The West Nile virus scare, and
several earlier instances of suspected bioterrorism, showed, as
well, the confusion and fear they can sow regardless of whether
or not they are validated.
- The threat to US forces and interests overseas also will
continue to increase as more nations develop a capability to
field at least limited numbers of biological weapons, and
nihilistic and religiously motivated groups contemplate opting
for them to cause maximum casualties.
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