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Mosquitoes Study Raises Question: Can Mosquitoes Transmit
Hepatitis C? June 1, 2000 Saturday, February 26, 2000 MOSQUITOES MAY SPREAD HEPATITIS Johannesburg, South Africa Startling research work by French scientists has shown that a potentially lethal form of hepatitis may be transmitted by mosquitoes. Hepatitis C, which can lead to chronic hepatitis as well as liver failure and liver cancer, is frequently seen in intravenous drug abusers and prostitutes. The disease, caused by a virus, does affect people with no history of drug abuse or prostitution however, and the route of infection for these people has baffled doctors. Dr Dominique Debriel studied whether the virus which causes hepatitis C can replicate in mosquito cells, and found that "the virus grows and reproduces better in mosquito tissue than it does in mammalian tissue." Dr Debriel was led to this line of research by the fact that hepatitis C belongs to the same family of viruses as two other mosquito borne viruses that cause human disease: yellow fever and dengue. All three of these viruses, yellow fever, dengue, and hepatitis C belong to the flavivirus group, and are capable of causing severe and on occasion fatal human disease. Dr Debriel presented his research at the 100th General Meeting of the American Society for Microbiology in Los Angeles this week. If hepatitis C is indeed transmitted by mosquitoes, there will be enormous public health implications. There could also be an enormous impact on the tourism industry, with tourists shunning countries with a high incidence of hepatitis C. Although there is believed to be a relatively high incidence of the disease in southern Africa, hepatitis C is not an exclusively developing country problem. Interestingly, there are some estimates that reckon two per cent of the American population may be infected with the virus. There is no vaccine available against hepatitis C. Although treatment is available against the virus, it works in only approximately one half of cases, and is extremely expensive. Comments Dr Andrew Jamieson, medical director of
British Airways Travel Clinics, Johannesburg - 26 May 2000 Hepatitis C From a Mosquito Bite? Could some unexplained cases of hepatitis C virus infection be caused by mosquitoes? Researchers have found that the virus can bind and replicate in mosquito cells, providing some evidence for that scenario. However, many experts disagree with the notion that mosquitoes may transmit the virus. Hepatitis C virus has infected about 170 million people worldwide; it inflames the liver, which can eventually lead to cirrhosis and cancer. The virus is transmitted mostly through infected blood products and dirty needles, but there's no obvious risk factor in as many as 20% of cases. Hepatitis C belong to the flaviviruses, a group that includes insect-borne viruses such as the West Nile virus, dengue fever, and yellow fever. That made a team led by Emmanuel Drouet at Université Joseph-Fourier Grenoble I in La Tronche, France, wonder whether hepatitis C could replicate in mosquito cells. The researchers took a hepatitis C virus isolated from an infected patient and added it to cells from the Aedes pseudoscutellaris mosquito and kidney cells from the African green monkey, both of which are commonly used to grow other flaviviruses. In the May issue of the Journal of Medical Virology, the team reports that the virus could bind and replicate in the mosquito and monkey cells, as measured by viral RNA levels, for as long as 28 days after infection. (In contrast, infection fizzled out in human B cells or liver cancer cells after about a week.) That suggests that mosquito transmission may be possible, Drouet says--although he notes that no one has found hepatitis C in intact mosquitoes. Given that hepatitis C is related to flaviviruses, it's "not a surprise" that the virus replicates in mosquito cells, says entomologist Michael Turell from the U.S. Army Medical Research Institute for Infectious Diseases in Fort Detrick, Maryland. Many scientists strongly dispute the mosquito transmission scenario. They point out that hepatitis C infections don't have the geographical or seasonal distribution expected if mosquitoes were responsible. Some of the "unexplained" cases, they argue, may simply be due to sexual transmission or reticence about drug use. "There still remains very little to support the notion that this is spread by mosquitoes," says epidemiologist David Thomas at Johns Hopkins School of Medicine. --ALKA AGRAWAL © 2001 by the American Association for the Advancement of Science. Dont' Let the Bed Bugs Bite, Literally J. Med. Entomol. 38(5): 694Đ700
(2001) In bugs inoculated intrathoracically,
HBV was detected for 21 d postinoculation. http://esa.edoc.com/medical/v38n5/v38n5p694.pdf
January 2003 Everyone knows that ticks spread Lyme disease. But hepatitis C virus? Scientists at the American Red Cross say they've made a circumstantial case for a tick passing the infection to a Connecticut woman who had no other obvious means of contracting the liver-damaging malady. "Ticks obviously ingest a fair amount of host blood and re-inject blood into the next animal or person they bite. They at least could act like little syringes," says Dr Ritchard Cable, medical director for the Red Cross's blood services centre in Connecticut, USA. He and his colleagues describe the case in a research letter in a recent issue of The New England Journal of Medicine. Possibly just coincidence Still, they have no better explanation for how the woman picked up the disease. She denies being infected on the job or having any high-risk lifestyle habits, such as multiple sex partners or drug use. The case study Yet when the woman gave blood five months later, hepatitis C appeared, a highly unusual event in regular donors. An August blood sample drawn as part of the study also turned up genetic evidence of the virus upon re-examination. When doctors spoke to the woman, Cable says, she revealed that she'd been ill in September with symptoms that were consistent with hepatitis C, including fatigue, stomach cramps, loss of appetite and dark urine. Intriguingly, she seemed to have acquired the infection during roughly the same window of time that she also picked up babesiosis, he says. The hepatitis C debate Even so, Schwan says catching hepatitis C from a tick bite would be "an extremely rare event that assumes many things" - including that the parasites are suitable hosts for the virus. "I would be very cautious" about concluding that the Connecticut case isn't one of mistaken infectivity, he adds. Hepatitis C, which can lead to fatal liver damage, typically causes no symptoms for years, earning it the nickname the "silent killer." Most infections occur in drug users sharing tainted needles. (HealthScout News) Read more: Can Ticks Spread Hepatitis C Virus? In an unusual case in Connecticut, doctors say they can't find any other reason why a woman got the liver disease. By Adam
Marcus WEDNESDAY, Nov. 20, 2002 (HealthScoutNews) -- Everyone knows that ticks spread Lyme disease. But hepatitis C virus? Scientists at the American Red Cross say they've made a circumstantial case for a tick passing the infection to a Connecticut woman who had no other obvious means of contracting the liver-damaging malady. "Ticks obviously ingest a fair amount of host blood and re-inject blood into the next animal or person they bite. They at least could act like little syringes," says Dr. Ritchard Cable, medical director for the Red Cross's blood services center in Farmington, Conn. He and his colleagues describe the case in a research letter in tomorrow's issue of The New England Journal of Medicine. Cable admits the connection could be coincidence. He has seen no other evidence of ticks ferrying hepatitis C from one person to another, nor to a person from an infected animal -- assuming that animals can contract the virus. What's more, it's not even clear the microbe can survive in ticks. Still, they have no better explanation for how the woman picked up the disease. She denies being infected on the job or having any high-risk lifestyle habits, such as multiple sex partners or drug use. The woman, a health-care worker and regular blood donor, was participating in a 1999 Red Cross study of a disease called babesiosis that's transmitted by deer ticks. Blood she gave in July 1999 tested positive for that disease, but not for hepatitis C. Yet when the woman gave blood five months later, hepatitis C appeared, a highly unusual event in regular donors. An August blood sample drawn as part of the study also turned up genetic evidence of the virus upon re-examination. When doctors spoke to the woman, Cable says, she revealed that she'd been ill in September with symptoms that were consistent with hepatitis C, including fatigue, stomach cramps, loss of appetite and dark urine. Intriguingly, she seemed to have acquired the infection during roughly the same window of time that she also picked up babesiosis, he says. Ticks do transmit at least one virus related to hepatitis C, causing tick-borne encephalitis, says Tom Schwan, an expert on the creatures at the National Institutes of Health's Rocky Mountain Laboratories in Hamilton, Mont. In Africa, ticks on rare occasions shuttle a disease called relapsing fever from person to person. Even so, Schwan says catching hepatitis C from a tick bite would be "an extremely rare event that assumes many things" -- including that the parasites are suitable hosts for the virus. "I would be very cautious" about concluding that the Connecticut case isn't one of mistaken infectivity, he adds. Hepatitis C, which can lead to fatal liver damage, affects nearly 4 million Americans. The disease typically causes no symptoms for years, earning it the nickname the "silent killer." Most infections occur in drug users sharing tainted needles. Screening of the blood supply has driven the rate of transfusion transmission, once a major problem, to less than one case per million units, according to the U.S. Centers for Disease Control and Prevention. What To Do To learn more about hepatitis C, try the U.S. Centers for Disease Control and Prevention. For more on the nation's blood supply, try the American Red Cross.
SOURCES: Ritchard Cable, M.D., medical director, American Red Cross Blood Services, Farmington, Conn.; Tom Schwan, Ph.D., senior scientist, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Mont.; Nov. 21, 2002, The New England Journal of Medicine Copyright © 2002 ScoutNews, LLC. All rights reserved. Thursday, 25 January, 2001, 16:54 GMT
'Japan bombed China with plague-fleas'
 Japan's wartime military ''bombed'' a Chinese city with bubonic plague
carrying fleas, triggering a serious outbreak of the disease, a doctor has
told a Tokyo court.
Bacteriologist Huang Ketai said at least 109 people had died from the plague in Ningbo in November and December 1940.
The disease broke out just days after Japanese warplanes dropped fleas over the city centre, the court heard. Dr Huang was giving evidence at a case in which 180 Chinese are demanding compensation and an apology from Japan for the deaths of their relatives during World War Two. The plaintiffs believe their family members were killed in biological experiments and acts of brutality carried out by Japan's notorious Unit 731. Dr Huang said the fleas, a kind not native to the region, were infected with "plague with artificially intensified toxicity", which he added only Unit 731 could do. Houses burned Lawyers for the plaintiffs say the fleas were dropped by air in a mixture with wheat. "Obviously, the outbreak was deliberately created," Dr Huang added. "It perfectly matches the area and the timing of the Japanese military's wheat dumping." The bubonic plague is normally spread by fleas on rats, but only one dead rat was found, he added. Also unusual was the fact that the outbreak was confined to such a small area. Dr Huang said infected houses, hospitals and other buildings in Ningbo were burned and had to be left untouched for decades. 'Japan should apologise' The lawsuit, filed in 1999, claims at least 2,100 people were killed in germ-bombings and other biological experiments by the unit and its affiliates. After decades of denial, Japan has now admitted that Unit 731 did exist, but it has refused to confirm its activities. Xuan Wang, a lawyer for the plaintiffs, said they were demanding Japan admit it carried out biological warfare and apologise. They are also asking for 10m yen ($86,670) each in compensation for the "mental suffering [caused by] biological warfare". The hearing at the Tokyo District Court is expected to continue for months. "I have devoted almost my entire life to the flea bombing probe," Dr Huang said in comments quoted by AP news agency. "Japan's government should at least apologise and compensate for our sufferings."
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Ticks
may spread Hepatitis C
