West Nile Epidemic Hits the U.S.

November 25, 2012 in Health & Lifestyle, Top News

Areas of the Continental U.S. affected by outbreaks of West Nile virus

Shown is a map from the Centers for Disease Control and Prevention demonstrating the distribution of West Nile virus outbreak as of November, 2012. Source: CDC.

An epidemic afflicts the United States at this very moment. West Nile virus exposures and resulting infections are reaching record numbers in 2012 according to the national Centers for Disease Control and Prevention. So far this year, a total of 5,207 cases of WNV disease in people have been reported, including 234 deaths and 2,643 cases of neuro-invasive disease. CDC expects the toll to exceed 2002′s record of 284 deaths and 2,946 cases of neuro-invasive disease.

Eighty percent of cases this year have been reported in Arizona, California, Colorado, Illinois, Louisiana, Michigan, Mississippi, Nebraska, New York, Ohio, Oklahoma, South Dakota and Texas. About one third of all reported cases are in Texas. Continued exposure to and infection by WNV is expected in the Southern U.S. through the end of 2012.

“Rain and flooding events can produce conditions that lead to explosive increases in mosquito populations, which in turn can pose a terrible nuisance to residents and those helping with recovery.  Aerial spraying of insecticide is sometimes used after hurricanes to control nuisance mosquitoes,” said CDC Director of Vector-borne Diseases Lyle Petersen in a September statement, explaining the lingering impact of Hurricane Isaac.

Also to blame for the increase in mosquito populations is the temperature.

“The smoking gun is the abnormally warm spring and summer this year. In many parts of the country, it was the hottest year on record,” Petersen said according to WebMD.

WNV is spread by mosquitoes who have bitten infected birds. The mosquitoes then spread the infection to animals and humans they bite later. People usually develop symptoms between 3 and 14 days after they are bitten by an infected mosquito.

About 1 out of every 150 persons exposed to WNV develops a serious illness. Symptoms include high fever, headache, stiffness in the neck, stupor, disorientation, convulsions, tremors, weakness, loss of vision, numbness, paralysis and coma. About 20 percent manifest less severe symptoms such as  fever, headache, body aches, nausea, vomiting, swollen lymph glands or a rash on the chest, stomach or back.

Symptoms can last several weeks resulting in permanent neurological damage. Less severe cases may last only a few days. Approximately 80 percent of those infected will exhibit no symptoms at all, however.

There is no specific treatment for WNV infection. Mild cases will resolve themselves. If you develop severe symptoms of WNV infection, such as unusually severe headaches or confusion, seek medical attention immediately. Severe cases require going to the hospital where patients can receive supportive treatment, including intravenous fluids, breathing support and nursing care.

CDC recommends several ways of protecting oneself from mosquito bites. These include using mosquito netting and screens, insect repellant and citronella-based candles or torches. Wear long sleeves and pants while outdoors, especially at dusk and dawn when mosquitoes are most active. Empty standing water from flower pots, buckets, barrels or any open container that can accumulate water. Drill holes in tire swings so water will drain. Keep children’s pools standing on their side when not in use. Change the water in pet dishes and bird baths at least weekly.

If you find a dead bird, do not handle it. Contact your local health department instead for instructions on reporting and proper disposal of the body.

For more information, call 1-800-CDC-INFO (1-800-232-4636), Monday-Friday, 8 a.m-8 p.m ET; or email cdcinfo@cdc.gov. (For TTY, call 1-888-232-6348.)