Mosquito Pool Tests Positive for West Nile Virus

A mosquito pool, sampled Aug. 4 in Buffalo Grove, has tested positive for West Nile virus. The mosquito pool is the first confirmed indicator of the disease's presence in Lake County in 2011. In 2010, one human and 29 mosquito pools tested positive for the virus in the county.

"While the weather may be getting cooler, mosquitoes are still active and will continue to be active until the first hard frost," said Irene Pierce, the health department's executive director. "It is important to protect yourself against mosquito bites even into the fall."

It is particularly important to practice mosquito bite prevention now since historically, human West Nile virus cases become more prevalent in the late summer and fall seasons. Culex mosquitoes, the mosquitoes that carry West Nile virus, are not associated with wet weather and the mosquito swarming that this area experienced earlier this year, but tend to thrive in dry conditions. 

Read: Tips to prevent mosquito breeding, bites

West Nile Virus Hotline

The Health Department maintains a West Nile virus hotline for county residents to report areas of stagnant water (which are conducive for mosquito breeding), or to obtain more information on the signs and symptoms of West Nile encephalitis. The West Nile hotline number is: 847-377-8300. 

While most people infected with WNV have no symptoms of illness, some may become ill, usually three to 15 days after the bite of an infected mosquito. In some individuals, particularly the elderly, the virus can cause muscle weakness, inflammation of the brain (encephalitis), stiff neck, stupor, disorientation, tremors, convulsions, paralysis, coma or death.

Mosquito Surveillance

The Health Department conducts a multi-faceted mosquito surveillance program in Lake County. Beginning in late spring and continuing into the autumn, a series of traps are set around the county, including within the Lake County Forest Preserves.

At each site a pool, or batch, of mosquitoes is tested weekly for West Nile virus. Areas of stagnant water are also investigated throughout the season for the presence of mosquito larvae, specifically from the Culex mosquito which is the primary carrier of West Nile in Illinois.

Finally, the locations of dead birds are monitored to assist in the assessment of potential West Nile virus activity. The Health Department works closely with the municipalities, townships, and the Lake County Forest Preserve District in monitoring the mosquitoes that may pose a public health threat.

For more information about WNV, visit: www.LakeCountyIL.gov

Information provided by Lake County Health Department