The Observer Newspapers | Mosquitoes Test Positive for West Nile in Fairfax

June 19, 2009

Mosquitoes Test Positive for West Nile in Fairfax

The Fairfax County Health Department announced that mosquitoes collected in the county have tested positive for the West Nile virus. It is the first time mosquitoes have tested positive for the virus in Virginia this year.

Recent heavy and persistent rains have provided breeding places for mosquitoes this year and the county's surveillance system is collecting an unusually high number of floodwater mosquitoes. The mosquitoes are very aggressive and attack during the daytime. The floodwater mosquitoes are not a normal part of the West Nile virus cycle.

The Culex mosquitoes that are regularly involved in the virus cycle prefer to feed on birds though occasionally feed on other animals such as horses or humans. Most mosquitoes do not carry the virus and many who are bitten by infected mosquitoes do not get sick. Those who do develop symptoms usually experience a mild, flu-like illness and older individuals are at greater risk for developing more severe injuries such as encephalitis or meningitis.

The county has treated more than 30,000 storm drains with an environmentally friendly larvicide, which inhibits mosquito breeding. More storm drain treatments are scheduled.