The Fairfax County Health Department has taken an active role in researching and monitoring mosquitoes across the county to identify carriers of the West Nile virus.
As of Aug. 11, the county department has confirmed two cases of the disease in two dead crows.
"Crows were the first indicator of the West Nile virus," said Jorge Arias, Fairfax County West Nile virus program supervisor. "But, so many birds have died off that it's not a good indicator anymore."
Arias said the first cases of West Nile virus were found in 1999 in New York, and spread from there. Fairfax County's first record of a case was in 2000 when a dead bird tested positive for the disease. In 2001 more birds in the county were found carrying the disease and in 2002 the hot, dry weather was perfect breeding for mosquitoes, which resulted in 13 human cases and one death from the disease, along with many horses being infected. Last year, the area had three human cases of the disease.
This year, no reported human cases have been reported in Fairfax County, only two dead birds and many mosquitoes have been confirmed to have the disease. Arias said the only reported human case in the state was in Roanoke.
"About 80 percent of people who get infected with West Nile virus will show no symptoms of the disease," said Arias. "Twenty percent will show mild, flu-like symptoms, and a small percentage will get West Nile meningitis or encephalitis, which is a swelling of the lining of the spinal cord and the swelling of the brain."
The county has been monitoring and researching the disease by collecting mosquitoes weekly through a West Nile virus monitoring program.
"Fairfax County has 70 sites with two different traps that are set each week," said Arias of the county's West Nile virus monitoring program. "So we have at least 140 traps that are collecting a lot of mosquitoes."
Arias said those traps are then sent to in-house laboratories where they are divided into smaller groupings and tested, and then possibly sent to a lab in Richmond where more specific West Nile tests can be run.
"THIS IS THE FIRST YEAR we have done good trappings; we have examined 41,000 [mosquitoes] so far this year," said Arias, adding their total collection for last year's peak mosquito season was 21,000.
Arias said the best way for people to reduce the risk of being bitten is to reduce the opportunity for mosquitoes to breed.
"The most important thing is source reduction," said Arias. "People need to get rid of any site that may house mosquitoes."
Arias said such sites include any area that collects and retains water, such as pet water dishes, bird baths, old tires, gutters or any type of storm water retention areas that are not flushed within a week.
"Anything that collects water at the house should be eliminated," he said, adding if some areas cannot be eliminated it is important the water is flushed through or changed once a week to stop the mosquitoes from hatching.
"Once mosquitoes have developed they are harder to kill," said Arias. "The best attack is in the water stage because you can get the eggs."
West Nile virus is most commonly found in Africa, West Asia and the Middle East and humans are infected by West Nile virus through mosquitoes that have contracted the disease by feeding on infected birds. The disease affects humans, birds, mosquitoes, horses and other mammals.
According to the Center for Disease Control and Prevention Web site, symptoms last a few days and can include a fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest stomach and back. More severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsion, muscle weakness, vision loss, numbness and paralysis. These can last several weeks and neurological effects may be permanent.
People over 50 are at greater risk to develop serious symptoms if they do get sick, and should take special care to avoid mosquito bites.
"This is here stay," said Arias of possibility that West Nile virus could disappear. "We will always have some mosquitoes."