Another Reason to Hate Mosquitoes
May 24, 2000 (Los Angeles) -- Each year, 36,000 people in the U.S. contract
the deadly hepatitis C virus, which infects the liver and is the leading cause
of damage requiring a liver transplant. The virus goes on to kill up to 10,000
Americans each year. Now researchers in France have evidence suggesting that
mosquitoes may spread hepatitis C and other viruses, such as West Nile virus.
The scientists discussed their work at a microbiology meeting here this
The people at highest risk of getting hepatitis C are drug abusers, people
who receive blood transfusions, patients who require kidney dialysis, and
health care workers. However, approximately 20% of people with the disease have
no risk factors for it at all.
Hepatitis C belongs to a family of viruses, such as the Dengue and yellow
fever viruses, that are known to be spread by mosquitoes, says co-author
Dominique Debriel, MD, PhD. But, he tells WebMD, "to my knowledge, no one
has yet shown [that mosquitoes transmit hepatitis C]."
To determine whether hepatitis C could grow in mosquito cells, Debriel and
his colleagues grew the virus in monkey cells, human cells, and mosquito cells.
They found that the mosquito cells were uniquely designed to connect with
hepatitis C, suggesting that these insects could indeed carry and transmit the
Debriel, a staff physician at the HÃ´pital Pasteur in Colmar, France, warns
that much more research must be done before it can be definitely concluded that
mosquitoes actually spread the disease.
However, this is no mere laboratory experiment. The havoc wreaked by a
mosquito-borne virus hit close to home last summer, when New York City was
swept by an outbreak of West Nile virus, another relative of hepatitis C.
Sixty-two cases of encephalitis, or inflammation of the brain, and seven deaths
occurred during that outbreak -- all thanks to the West Nile virus carried by
According to the CDC, this was the first report of a West Nile virus
outbreak in the U.S. As its name implies, the virus is most commonly found in
Africa, West Asia, and the Middle East. Its fatality rate can range from 3% to
15% and is highest in the elderly.
Unfortunately, says Debriel, the symptoms are similar to another form of
encephalitis caused by herpes and other viruses, so doctors needed a way to
make an accurate diagnosis -- fast.
During the New York City outbreak, Debriel and his colleagues developed a
test for identifying viruses in the family that includes hepatitis C and the
West Nile virus. "By analyzing samples of a patient's blood and [brain and
spinal fluid], we can diagnose encephalitis due to [a virus from this family]
within just a few hours. Rapid diagnosis of these patients is important because
they must be isolated and treated quickly."