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McLean County Health

200 W. Front St.
Bloomington, IL 61701
Ph: (309) 888-5450
Hours: Monday-Friday
8:00 AM - 12:00 PM
1:00 PM - 4:30 PM

West Nile Virus


About the Virus
West Nile virus (WNV) is a mosquito-borne disease that can cause encephalitis, or an inflammation of the brain. Infected culex mosquitoes pass the virus onto birds, other animals, and people. West Nile virus was first detected in the United States in New York during the fall of 1999 and in Illinois in 2001. Prior to arrival in the United States, the virus had only been found in Africa, Eastern Europe, and West Asia.

West Nile virus cases occur primarily in midsummer or early fall, although mosquitoes that carry the disease may be present from mid-April through October. During the 2005 mosquito season, McLean County experienced four cases of West Nile virus resulting in two deaths.

2014 McLean County WNV Numbers

Areas Tested


Tested birds


Positive birds


Tested mosquito pools


Positive mosquito pools


Positive human cases


Human deaths related to WNV


Positive horses and other animals


WNV Symptoms
West Nile virus encephalitis is transmitted from infected mosquitoes to people, not from person to person or from bird to human. Mosquitoes get the virus by feeding on infected, migratory birds. Mild cases of West Nile virus may cause a slight fever or headache. More severe infections are marked by a rapid onset of a high fever with head and body aches, disorientation, tremors, convulsions and, in the most severe cases, paralysis or death. Symptoms typically occur from three to 14 days after the bite of an infected mosquito.

High-Risk Individuals
Individuals at highest risk for serious illness are very young children, adults 50 years of age or older, and people with compromised immune systems. Anyone concerned about their risk or experiencing two or more symptoms should contact a physician immediately and inform the doctor of any recent mosquito bites.

Fight the Bite! Steps to Prevent West Nile Virus
High-risk areas include: 
  • Anywhere outside at dusk and dawn, when the culex mosquitoes are most active.                  
  • Standing pools of water that harbor mosquito breeding such as bird baths, ponds, lakes, flowerpots, wading pools, and old tires.
  • Locations with windows or doors with loose fitting screens or with holes or tears in the screens.

Reduce risks by taking these precautions:
  • Avoid being outdoors at dusk and dawn.
  • If outdoors at these times, wear protective clothing such as shoes and socks, long pants, and a long-sleeved shirt.
  • Apply insect repellent that includes DEET, lemon eucalyptus oil, or picaridin according to label instructions. Consult a physician before using repellents on young children. 
  • Repair or replace screens that have tears or other openings. 
  • Eliminate all sources of standing water. 
McLean County Surveillance 
The McLean County Health Department will monitor virus activity in birds and mosquitoes during mosquito season, which runs approximately May through October. In May, the McLean County Health Department begins collecting dead birds excluding predators like owls, hawks, falcons, and eagles. Residents who find a dead bird on their property during mosquito season should: 
  • Find out if the department is still accepting birds for testing - Contact the Environmental Health Division at (309) 888-5482 to find out if the department is still accepting birds for testing. The department can only collect and test a limited number of birds. Birds eligible for testing must be dead no longer than 24 hours and must have no obvious signs of trauma. Those submitting birds will receive further instruction upon calling the Environmental Health Division.
  • Dispose of a dead bird that the health department cannot accept - Adults should use gloves and/or tongs to place the dead bird inside two plastic bags. Then, place the deceased bird into the trash or bury it away from water sources. After handling a dead bird, washing your hands with soap and warm water is essential.

Contact Us
For more information, contact the Environmental Health Division at (309) 888-5482 or visit the Illinois Department of Public Health WNV website.