Mosquitoes in Northern Virginia have tested positive for the West Nile virus, which last year killed one Virginian and one person in Maryland.
Prince William County announced Monday that mosquitoes tested positive for the disease in Woodbridge. And Fairfax County officials said they found four groups of mosquitoes that also tested positive. Maryland officials have not yet started testing mosquitoes.
In addition to the two fatalities last year, 19 people contracted the virus in Maryland in 2011, plus nine in Virginia and 15 in D.C.
The virus can lead to simple flulike symptoms, or it can lead to swelling of the brain and other severe problems. People age 50 and older are most at risk, health officials said. Severe symptoms include high fever, convulsions, vision loss and paralysis.
The virus has been making a summertime appearance in the Washington area for more than a decade. Officials recommend residents use insect repellent and wear long, loose, light-colored clothing when working outdoors.
"I think people, when they're out working in the yard or walking outside, they forget that they're vulnerable to mosquito bites," said Cindy Edwards, a nurse who works for the Montgomery County's Health Department. "You never know. Usually the elderly have the biggest problems, but you never know."
Health officials also urge people to eliminate standing water from around their homes by cleaning out rain gutters and flowerpots.
"Pretty much anywhere there is as little as a quarter of inch of standing water is enough for a female mosquito to lay her eggs," said Kim Mitchell, who monitors West Nile for the Maryland Department of Health and Mental Hygiene. "That can happen anywhere -- any county, any ZIP code."