Mosquitoes collected this month by the Prince William Mosquito Control Program have tested positive for the West Nile Virus, marking the first time that the virus has been documented in the county this year, according to a statement by officials with the Virginia Department of Health.

Health department officials urged members of the public to eliminate standing water — where mosquitoes breed — and guard against mosquito bites, after insects carrying the virus were collected from test areas in Woodbridge, according to the statement.

The mosquito testing is used to determine when the public may be at greater risk of contracting West Nile Virus, and the wide occurrences of virus-positive mosquitoes indicates that there is an increased risk of contracting the virus across Prince William County, officials said.

West Nile Virus is a mosquito-borne disease that spreads to birds, humans, horses and other mammals through the bite of an infected mosquito. Most people bitten by an infected mosquito do not get sick, and those who get sick usually suffer mild, flu-like symptoms, the statement said. Those older than age 50 are at greatest risk of serious illness, such as encephalitis — inflammation of the brain — or meningitis, an inflammation of the lining of the brain and spinal cord. Very few people who contract the virus suffer from these more severe symptoms, and there was only one confirmed human case of West Nile Virus disease reported in Prince William County in 2013, according to the statement.

Local residents can play a big role in disease prevention by paying special attention to eliminating mosquito breeding areas and protecting themselves from mosquito bites while outside, officials said.

“Since most of the mosquito species that residents need to control breed in standing water within a few hundred feet of their residence, control measures around the home are the most effective way to prevent mosquito breeding and to reduce the risk from bites,” said Alison Ansher, director of the Prince William Health District, in the statement.

Mosquitoes will continue to be trapped and tested regularly from sites in Prince William County. The County’s Mosquito Control Program has performed intensive treatment in the vicinity of the positive mosquito pools with the aim of killing adult and larval mosquitoes and preventing further spread of the virus, the statement said.

The Prince William Health District recommends that residents take the following steps to reduce exposure to mosquitoes:

• Wear long, loose and light-colored clothing.

• Use insect repellent products with no more than 50 percent DEET for adults and less than 10 percent for children. Follow label instructions when using insect repellents.

• Turn over or remove containers in your yard where any water may collect, such as old tires, potted plant trays, buckets and toys.

• Eliminate any standing water in yards or on tarps or flat roofs.

• Chlorinate or clean out birdbaths and wading pools every three to five days.

• Clean roof gutters and downspout screens regularly. Mosquitoes breed and feed in standing water in roof gutters.

The Prince William Mosquito Control program will continue its mosquito control efforts throughout the summer as needed, the statement said.