West Nile Virus in U.S.: Woman Dies in Iowa, Infected Mosquitoes in Massachusetts

Mosquitoes infected with the potentially deadly West Nile virus have been detected across the country this month, with cases reported in Massachusetts, Virginia and Iowa.

Local health departments have issued warnings on how to stay safe from mosquito-borne illnesses after an Iowa woman died from West Nile virus, which state officials confirmed last Friday. On the same day, health officials in Massachusetts said that seven mosquitoes had tested positive for the virus in Greenfield, a small city in the western part of the state. Another person became sick with the virus last week in Fairfax County, Virginia.

West Nile virus is spread to people through mosquito bites. In North America, cases of the virus occur during mosquito season, which starts in the summer and continues through fall, according to the Centers for Disease Control and Prevention.

Symptoms include high fever, body aches and vomiting. In the most severe cases, people may experience swelling in the brain and paralysis or even die. Most people recover within weeks or months. About one in five people who are infected develop a fever and other symptoms. Others may never show any symptoms. Only about one out of 150 infected people develops a serious, sometimes fatal, illness, according to the CDC.

While people of any age can become sick with the virus, those over 50 and people with weak immune systems are at highest risk, according to the World Health Organization. There is no vaccine to prevent infection, and there are no medications to treat the virus.

Iowa Deputy State Epidemiologist Ann Garvey said in a statement from the health department that the recent death should serve as a warning for people to avoid getting bitten by mosquitoes.

Local health departments in recent days have advised that people avoid outdoor activities after dusk, when mosquitos are most active; apply bug spray when going outdoors and wear long sleeves.

Those who want to make sure bugs aren't breeding near their homes should drain any standing water outside—including water in outdoor buckets, cans, pool covers and pet water dishes—where mosquitoes lay their eggs. Change the water in birdbaths at least every four days.

"Until the state's first hard frost, whether it's for work or play, being outside means there's a risk for West Nile virus," Garvey said in a statement.