Mosquitoes collected on Aug. 15, 2023 near Morrison, Ill., have tested positive for the West Nile virus, according to Rian Nailor, director of environmental health for the Whiteside County Health Department.

A positive mosquito pool is significant since Culex mosquitoes have a very short flight range of approximately ¼ mile, according to a Thursday health department release. It is likely that West Nile is also circulating in other areas of the county, however, a positive test tells for sure that there are infected mosquitoes buzzing around Morrison, putting residents at greater risk of exposure.

West Nile virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird. Typically, August and September is when WNV activity is at its highest and the threat of West Nile exposure can remain until the first frost, the release said.

Since it is now the peak season for mosquito borne disease, it’s important for the public to continue their vigilance and take some simple precautions to reduce the number of mosquitoes around your home and protect themselves from exposure. 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 and repair or replace any with tears or openings.

● Try to keep doors and windows shut, especially at night.

● Eliminate all sources of standing water where mosquitoes can breed, including flowerpots, wading pools, old tires, clogged rain gutters, old boats and any other receptacles and change the water in bird baths weekly.


● Wear shoes and socks, long pants and long sleeved shirts when outdoors.

● Apply insect repellent that contains DEET, picaridin, oil of lemon eucalyptus or IR 3535, according to label instructions when outdoors. Consult a physician before using repellents on infants.


● Report dead birds to the Whiteside County Health Department.

● If your community has an organized mosquito control program, contact your municipal government about areas of stagnant water in roadside ditches, flooded yards, and similar locations that may produce mosquitoes.

For more information on West Nile, visit the IDPH website HERE.