August 16, 2011 — If you are bitten by a mosquito and feel sick, it may be West Nile virus.

Reports of West Nile virus peaked in August since it emerged in the United States in 1999. The incubation period is 2 to 14 days, and the next infection may come from a mosquito circling outside your door.

3 West Nile deaths have been reported so far this year – 2 last week. 32 cases of severe West Nile encephalitis, meningitis or polio-like disease so far Flaccid paralysis cases. The CDC estimates that for each such case, there are 26.5 cases of milder West Nile fever — meaning there are an estimated 848 cases this year.

But it’s hard to know from these preliminary data how bad this year’s West Nile really is, says Marc Fischer, MD, MPH, MD, director of surveillance for the CDC’s division of surveillance that tracks mosquito- and tick-borne diseases. , this season will come.

“Typically, nationally, West Nile cases peak around this time of year, around mid-to-late August,” Fischer tells WebMD. “But there can be a delay of weeks before a report is submitted to the CDC, so it’s hard to say what kind of season it is.”

Various factors limit the accuracy of the report. Some depend on which parts of the country are getting the hot and humid weather patterns that mosquitoes prefer. Some rely on mosquito outbreaks, which can be very localized and can overwhelm local health departments when funding is cut. Still others depend on whether doctors test for West Nile virus, as symptoms of mild or even more severe illness are similar to others.

In 2007, case reporting had its fastest start ever, but the year didn’t turn out to be as bad as 2003, when nearly 10,000 cases were reported and 232 people died.

The West Nile has spread from coast to coast. Last year, 1,021 cases of West Nile disease were reported. The CDC estimates that for every reported case, 140 people are infected. Four out of five of these infections were asymptomatic. Only one in five people will get sick, and the chance of getting sick after infection increases with age.

15 West Nile states have reported disease so far this year: Arizona, California, Colorado, Florida, Georgia, Indiana, Louisiana , Mississippi, Nebraska, North Dakota, South Dakota, Texas, Virginia and Wyoming. The three deaths were in Florida, Mississippi and Texas.

But this year, 240 counties in 34 states have detected West Nile virus in humans, livestock, birds, sentinel animals or mosquito pools. West Nile virus detected in donated blood in 15 states, routine testing in U.S.

“West Nile virus is now spreading in the U.S. Lack of surveillance reports does not mean a real lack of activity,” Fisher “This is the peak time of the year and everyone should take steps to prevent mosquito bites,” Ernst warned.