West Nile Virus Prevention and Symptoms

UPDATE (July 22, 6 a.m.): Mosquitoes trapped on July 8 have tested positive for West Nile Virus in northern Woodbridge and Lake Ridge. We're reposting this as an advisory.

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Earlier this week, Prince William County announced that additional mosquitoes have tested positive for West Nile Virus. Mosquitoes trapped on July 20-21, 27 and 29 have tested positive for the virus in addition to those trapped in Woodbridge on July 8 - 9. 

Health Director Dr. Alison Ansher made the original announcement, which also noted the first mosquitoes tested positive for the virus were identified last summer in late August.

Tim McGonegal, Branch Chief of the Gypsy Moth and Mosquito Control, said that West Nile Virus usually makes an appearance in July and August, peaks in late July, early August and then goes down considerably in the early fall months.

"It's really nothing too new, since the first couple years it was very alarming because we had numbers," said McGonegal. "We know it's established in the area, because it has been here year after year but we do like to keep an eye on it to make sure that we're not finding a lot of new mosquito populations because as that increases it increases the potential for human disease. "

The mosquito control group, a division of the Prince William County Public Works department, does not monitor for human infection. Instead, the health department and resident's personal physicians diagnose the virus; although McGonegal's division does keep an eye out for human infection statistics.

McGonegal notes that human West Nile Virus cases show up later in the season, around August or September.

"West Nile is, as far as mosquito-transmitted diseases go, is relatively mild if you're middle-aged, in good shape, basically it would feel like a cold, maybe a flu," said McGonegal. "A lot of people probably have had West Nile, have not been diagnosed, and get a fever and headache."

Those with immune deficiencies and the elderly are at the highest risk for West Nile Virus. The cold-like symptoms could be long-standing and in rare cases, could result in death.

In Manassas, one human case of West Nile Virus was reported in 2009 as well as four others in Virginia but there were no human deaths as result of the virus.

To help prevent the spread of West Nile Virus, and the birth of more mosquitoes that may carry the virus, McGonegal recommends emptying any standing water in and around homes in any containers such as buckets, wheelbarrows, flower pots and bird baths.

"It really helps us out," said McGonegal. "Those are the areas where a lot of these mosquitoes that can carry West Nile lay their eggs and develop and breed in those areas."

Prince William Health District recommends wearing long, loose and light-colored clothing in addition to insect repellent products with no more than 50 percent DEET for adults and less than 10 percent DEET for children.

For more information about West Nile Virus, visit the Virginia Department of Health.