Fewer cases of West Nile virus were reported in the United States in 2013 compared with the previous year, the Centers for Disease Control and Prevention said Thursday.
Last year, there were 2,469 reported U.S. cases of the mosquito-borne virus, compared to 5,674 cases in 2012, when there was a large outbreak of the disease, the agency reported.
According to the CDC:
- About half of the 2013 cases were severe — causing inflammation in the brain or surrounding tissues.
- Cases peaked in September, and 90 percent of the people infected with the virus became ill between July and September.
- More than half (51 percent) occurred in just six states: California, Texas, Colorado, Illinois, North Dakota, and Oklahoma.
- The states with the highest rates of severe cases relative to their populations were North Dakota, South Dakota, Nebraska, and Wyoming.
West Nile virus is most commonly spread by mosquitoes. Most people infected with the virus have no symptoms, but some develop a fever, headaches, body aches, and other problems. Fewer than 1 percent develop neurological illness, according to the CDC.
To prevent infection with West Nile, the CDC recommends using insect repellant and wearing protective clothing.
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