Mosquitoes Test Positive for West Nile Virus

July 14, 2008

News Highlights

  • Two mosquito samples collected last week in Mason District have tested positive for West Nile virus.
  • First positive mosquito samples identified this year.
  • West Nile virus is still active; residents are encouraged to eliminate mosquito breeding areas.

More Information 

The Fairfax County Health Department today announced two mosquito samples collected last week in Mason District tested positive for West Nile virus. These are the first positive mosquito samples identified this year in the county.

"This is a reminder to residents that West Nile virus is still active in Fairfax County and now is the time for people to pay close attention to eliminating mosquito breeding areas around their neighborhoods," said Gloria Addo-Ayensu, M.D., M.P.H., health director. "Removing breeding sites by tipping and tossing standing water protects everyone and reduces the risk of infection for the whole community."

West Nile virus is spread to birds, humans, horses and other mammals through the bite of infected mosquitoes. Most people bitten by a mosquito infected with West Nile virus do not get sick. Those that develop symptoms usually suffer a mild, flu-like illness. People over the age of 50 are at greatest risk of more severe illness, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord).

According to Jorge Arias, Ph.D., Fairfax County environmental health entomologist, the species identified were the Culex pipiens, known as the northern house mosquito, and the Culex restuans, or the white dotted mosquito. Both are predominately bird biters and considered principle vectors of the West Nile virus.

"We are closely monitoring mosquitoes this year and have tested more than 60,000 so far, looking for West Nile virus and other arboviruses," said Arias.

The Fairfax County Health Department’s Environmental Health staff are taking a proactive approach to combating West Nile virus by treating more than 35,000 storm drains three times a year with an environmentally friendly larvicide that inhibits mosquito breeding. Storm drain treatments are scheduled throughout the mosquito season, which typically runs from May until October. While these treatments will not eliminate all of the mosquitoes that carry the virus, the mosquito population will be reduced.

Fairfax County has an active outreach and education program and staff are aggressively promoting the mosquito management campaign, "Fight the Bite: Say NO to MOsquitoes." A number of educational materials have been developed for English and non-English speaking residents.

The Health Department recommends the following tips for residents to reduce exposure to mosquitoes:

  • When spending time outdoors, use insect repellents containing the active ingredient DEET (up to 30 percent), picaridin, oil of lemon eucalyptus or IR-3535. Always use mosquito repellents according to label instructions.

  • Wear long, loose-fitting, light-colored clothing.

  • Turn over or remove containers in the yard where water collects, such as old tires, potted plant trays, buckets and toys.

  • Fill in root-ball holes from downed trees or any depression that holds water for more than a week.

  • Eliminate standing water on tarps, such as those that may be used to cover wood piles.

  • Clean out birdbaths and wading pools once a week.

  • Clean roof gutters.

  • Manage black corrugated drain pipes.

For further information, residents may call the Health Department’s Disease Carrying Insect Program at 703-246-2300, TTY 703-591-6435.


Fairfax County Office of Public Affairs
12000 Government Center Parkway, Suite 551
Fairfax, VA 22035-0065
Contact: Merni Fitzgerald, Director of Public Affairs
703-324-3187, TTY 711, Fax 703-324-2010
Media Pager: 703-324-NEWS (6397)

Fairfax County is committed to nondiscrimination on the basis of disability in all county programs, services and activities. To request this information in an alternate format, call the Office of Public Affairs at 703-324-3187, TTY 711.

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