Four crows found dead in Loudoun County since the beginning of July have been confirmed to have West Nile virus. The birds are the first sign of West Nile in Loudoun this year. Last year, there were 29 cases of the virus and two fatalities in Virginia, with two of the cases and one of the fatalities in Loudoun.
"It's not an unexpected finding," said Dr. David Goodfriend, director of the county Health Department, who announced the first two positive birds on July 3. Given the presence of West Nile in the area last year, authorities have anticipated renewed activity. The cold, wet spring likely postponed the first cases of the year, said Goodfriend.
West Nile virus is transmitted by mosquitoes, which feed off both humans and birds. The virus first emerged in the United States in 1999 in New York, spreading to Virginia through birds the next year. In 2001 Loudoun reported its first West Nile positive birds, and last year the county had its first West Nile positive mosquitoes and cases in humans and horses.
A small percentage of humans who are bitten by infected mosquitoes get sick, and those that do usually only encounter a minor, flu-like illness. Senior citizens and people with medical conditions are at the greatest risk of serious illness like encephalitis or meningitis.
MOSQUITO SURVEILLANCE has been implemented in Loudoun and Goodfriend expects positive-tested mosquitoes to follow within the month. Adult mosquitoes caught in traps are tested for the presence of West Nile virus. Mosquitoes are fairly stationary, with a range of less than a mile, so traps are placed in the areas of highest risk, as mosquitoes in more isolated areas pose less of a threat to people. "We are concerned about mosquitoes around houses, schools, hospitals and assisted living facilities," said John Neely, Mid-Atlantic operations manager for Clarke Mosquito, which claims to be the world's largest mosquito-control company; and has contracts with Loudoun County and the Town of Leesburg.
The Town of Leesburg has six traps and places a biodegradable nontoxic larvicide in 3,300 storm-water catch basins three times a year, said Steve Cawthorn of the Town Utilities Department. Loudoun County places larvicide in more than 10,000 catch basins overall. Cawthorn said the county and town cooperate to reduce the mosquito population and thus the risk lowers "for both citizens and visitors."
GOODFRIEND STRESSES the importance of everyone helping out in the fight against West Nile. The numbers of mosquitoes in the community has risen sharply in the past four weeks as drier weather and warmer nights are better mosquito breeding conditions. Citizens are asked to report crows, blue jays and raptors that may have died from West Nile within 24 hours of death. Also, citizens can remove standing water, which breeds mosquitoes, around their houses, and are advised to wear insect repellent. "No matter how many mosquitoes are infected, if no one gets bitten by a mosquito, no one will get West Nile," said Goodfriend.