The DuPage County Health Department has announced that the first positive tests for West Nile virus (WNV) this year have been discovered in mosquito traps in Hinsdale, Clarendon Hills, Westmont, Lisle and Woodridge.
These are the first mosquitoes that have tested positive in Illinois this year.
According to Dr. Deepti Chauhan, only 20 to 40 percent of patients come down with symptoms of West Nile virus after being bitten by an infected mosquito, and less than one percent have severe symptoms. Chauhan is an Infectious Disease Specialist with the Loyola University Health System, which has .
"The majority of people [exposed to West Nile Virus] are asymptomatic," said Chauhan, who is based at Loyola's campus in Maywood. She said people who are immuno-compromised, pregnant or elderly are most at risk for experiencing symptoms, which can become severe.
According to the DuPage County Health Department, only about two people in 10 who are bitten by an infected mosquito will experience any illness. Serious illness, such as encephalitis, meningitis and death are possible in individuals over the age of 50.
How to know if you have West Nile Virus
Chauhan said the symptoms of West Nile Virus are very similar to those of the flu, so she looks for a combination of factors to diagnose whether a patient is infected, along with a blood test.
"I look for a constellation of symptoms together," said Chauhan, "If a person experiences fevers, headaches, body aches, rash, complains of feeling tired after being bitten by a mosquito—especially in a person who doesn't have an upper respiratory infection ... we test for antibodies against the virus in the blood. If antibodies are present, there is a strong indication that it is West Nile."
Chauhan said that a person who experiences these symptoms for two weeks after outdoor exposure should come in to get a blood test.
"It takes up to a week for the antibodies to show up in the blood," said Chauhan, "so a test could initially come back negative, and a person could still have it."
Chauhan said the incubation period is 2 to 14 days, and the maximum incubation period for WNV is two weeks.
Chauhan said in our area, West Nile becomes a consideration in diagnosing a patient's illness during the spring and summer months.
According to the DuPage County Health Department the West Nile Virus-positive mosquitoes are being reported earlier than usual this year due to the warm weather conditions. The health department said West Nile Virus is weather dependent so the early positives were expected.
DuPage County residents who want to track West Nile Virus in their communities can do so by utilizing this surveillance map. This map of mosquito traps throughout the county will be updated as mosquitoes test positive.
No human cases of West Nile Virus have been reported in DuPage County so far in 2012.
The Health Department is collecting freshly-dead birds (such as crows or blue jays) for West Nile Virus testing. The birds must not show any signs of decay or trauma. To report a dead bird, call (630) 682-7400.
How to prevent getting infected with West Nile Virus
West Nile Virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird.
Chauhan said that this is the only way people can become infected.
"It's not spread through kissing, touching, sharing utensils," said Chauhan.
The best way to prevent West Nile Virus or any other mosquito-borne illness is to reduce the number of mosquitoes around your home and to take personal precautions to avoid mosquito bites. Precautions include practicing the three “R’s” – reduce, repel and report:
- REDUCE exposure - avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.
- Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.
- Eliminate all sources of standing water where mosquitoes can breed, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles.
- REPEL - when outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that contains DEET, picaridin, oil of lemon eucalyptus or IR 3535, according to label instructions. Consult a physician before using repellents on infants.
- REPORT - In communities where there are organized mosquito control programs, contact your municipal government to report areas of stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.