West Nile outbreak huge

ATLANTA -

The current West Nile outbreak could be one of the largest in U.S. history, with four times the usual number of cases for this time of year, federal health officials said Wednesday.

It's still too early to say how bad the year will end up because most infections are reported in August and September. But never before have so many illnesses been reported this early, said Dr. Lyle Petersen, of the Centers for Disease Control and Prevention.

So far, 1,118 illnesses have been reported, about half of them in Texas. In an average year, fewer than 300 cases are reported by mid-August. There have also been 41 deaths this year, the CDC said.

And cases seem to be accelerating: About 400 of the cases were reported in just the past week.

Experts think the mild winter, early spring and very hot summer helped stimulate mosquito breeding and the spread of the virus. Mosquitoes pick up the virus from birds they bite and then pass it on to people.

CDC officials are also looking into the possibility that the virus mutated, but so far have no information showing that happened, Petersen said.

Only about 1 in 5 infected people get sick.