
A dipper is used to trap mosquito eggs, larvae and pupae, according to Dave Zazra, the communications manager for the North Shore Mosquito Abatement District. Image courtesy of North Shore Mosquito Abatement District.
We survived one of the coldest Aprils on record, sloshed through a wetter May than normal and were still wearing sweaters beyond the first week in June – but that’s not all!. If you’ve been outdoors for any length of time lately, you’ve probably noticed the mosquitoes are out – and they are biting. This is annoying for sure – and itchy — but it also can be risky, because the house mosquito, more formally known as the blood-feeding Culex pipiens, is a vector of West Nile Virus and Western Equine Encephalitis – among other diseases.
And WNV already has been detected in Illinois. The North Shore Mosquito Abatement District found it in traps in Glenview and Morton Grove during the week of May 19 to May 21. Both the abundance of Culex pipiens and the WNV infection rate of 0.85 infected mosquitoes per 1,000 tested were above average for that time of year, according to Dave Zazra, communications manager for the district.
It’s worth noting that the following week, the district did not detect any WNV in its traps.
But you still should be vigilant about protection.
“As we see higher temperatures, we will start to see more West Nile virus activity,” said Illinois Department of Public Health Director Nirav D. Shah, M.D., J.D. “Although we see West Nile virus in Illinois every year, don’t become complacent. It’s easy to take precautions to protect yourself by wearing insect repellent and getting rid of standing water around your home.”
Mosquitos that carry WNV got it from feeding on an infected bird — so if you see a sick or dying crow, blue jay, robin or other perching bird, it could be a sign that WNV is in the area. You should contact your local health department, which will determine if the bird will be picked up for testing. (Same goes for sick or dying bats, which could have rabies.)
Monitoring for WNV in Illinois includes laboratory tests for mosquito batches, dead perching birds, as well as testing sick horses and humans with West Nile virus-like symptoms, according to the IDPH.
Common symptoms include fever, nausea, headache and muscle aches. Symptoms may last from a few days to a few weeks. However, four out of five people infected with West Nile virus will not show any symptoms. In rare cases, severe illness including meningitis or encephalitis, or even death, can occur. If you are over 60 or have a weakened immune system you are at higher risk for severe illness from WNV.

Mosquito test batch
Photography by Joel Lerner/JWC Media

North Shore Mosquito Abatement District’s Christopher Xamplas collects mosquito specimens from traps throughout the area and tests them for West Nile virus. Photography by Joel Lerner
To help prevent mosquitoes from breeding around your home and business and to protect yourself from bites, follow the “4 Ds of Defense”:
Drain: Drain standing water from items around your home, yard, and business.
Defend: When outdoors, use an insect repellent containing DEET, picaridin, or IR3535 and reapply according to label directions.
Dawn and Dusk: Protect yourself all day and night, and wear repellent outdoors during these prime times for mosquito activity.
Dress: Wear long sleeves, pants, and closed toe shoes when outdoors to cover your skin.
Since 2002, there have been 64 confirmed human cases of West Nile virus in Lake County, as well as two confirmed deaths.