West Nile virus is sweeping the United States this year. As of October 2, 2012, 48 states have reported West Nile virus activity in mosquitoes, birds or people - all but Alaska and Hawaii.
There have been a total of 3,969 human cases of West Nile virus reported, including 173 deaths. About 70 percent of all cases come from eight states: Mississippi, South Dakota, Michigan, California, Louisiana, Oklahoma, Illinois and Texas. A third of cases have been reported from Texas.
This year's cases are the highest numbers reported through the first week in October since 2003.
In this image, mosquitoes are sorted at the Dallas County mosquito lab in Dallas, Thursday, Aug. 16, 2012.
Credit: LM Otero