Ominous Start for West Nile Season
West Nile Virus 2007: Fastest Start Yet for Mosquito-Borne Illness
Because so many infections have no symptoms, the CDC's official case count
is a huge underestimate. But nearly every case of West Nileencephalitis or meningitis (affecting the brain or lining around the
brain) is reported -- so by multiplying the number of these cases by
150, it's possible to get a rough estimate of the true number of
So far this year, there have been 42 cases of neuroinvasive West Nile
infection. That suggests there have already been about 6,300 total infections
with West Nile. By the end of worst year, 2003, there were 2,866 reports of
neuroinvasive disease, suggesting there were nearly 430,000 infections.
Whether this year will be as bad as that depends largely on the weather.
Birds carry West Nile virus, and mosquitoes get the bug after feeding on birds.
The virus then has to grow inside the mosquito to levels infectious to humans.
This happens most efficiently in hot weather.
If August and September are relatively cool, the bug might not be a big
problem. But that's just speculation. The U.S. history of West Nile virus is
too short for scientists to make accurate predictions.
One prediction can be made for sure: You will have a much lower risk of West
Nile infection if you avoid
"From the early numbers, it looks like we have a pretty busy West Nile
season going," Zielinski-Gutierrez says. "Get out that repellent. The
take-home message at this point for the American public is, 'Whoa -- there
seems to be a lot of West Nile out there. When I go out there I'd better do
something to keep from getting mosquito bites.'"