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Monitoring for West Nile Virus

Post Date:07/24/2019 1:02 PM

WOODSTOCK - Summer is well underway and along with it mosquito season. McHenry County Department of Health (MCDH) wants residents to protect themselves from mosquito bites during outdoor activities. The Culex mosquito, most active at dawn and dusk, is the primary vector for West Nile Virus (WNV) transmission.

Most people exposed to WNV have no symptoms. About 20% of infected people develop mild symptoms, typically a mild flu-like illness. Symptoms include mild fever and headache, body aches, nausea, vomiting, skin rashes, and swollen glands. Roughly one in 150 infected people develop severe symptoms, which can include a severe headache, high fever, stiff neck, delirium, muscle weakness, tremors, seizures, coma, and paralysis. These symptoms can last for several weeks and sometimes result in hospitalization, permanent neurological effects, or death. Individuals over 50 or with serious underlying health conditions are at higher risk for developing severe symptoms. See your healthcare provider if you develop these warning signs. There is no vaccine available for West Nile Virus.

Culex mosquitoes typically breed in artificial containers of stagnant water such as storm drains, non-chlorinated swimming and wading pools, bird baths, flower pots, buckets, clogged gutters and abandoned tires. The first and best defense against mosquito-borne illness is to eliminate potential mosquito breeding sites on your property by preventing water from accumulating in containers.

When outdoors, wear protective clothing such as light colored long sleeved shirts, socks and pants. Limit outdoor activities during the evening and early morning, when Culex mosquitoes are most active. Use insect repellents approved by the EPA:

  • Repellents containing 20% or more DEET (less for children) are effective.

  • Repellents including oil of lemon eucalyptus or Picaridin may be used as an alternative to DEET.

  • Apply repellents per label directions. Consult with a doctor before using any repellant on infants.

From May through October Health Department staff conducts West Nile Virus surveillance throughout the county. Mosquito batch collections and testing are conducted weekly. In addition, MCDH tests a limited number of dead birds. Contact the Division of Environmental Health at 815-334-4585 if you find a dead blue jay, crow or robin. Bird specimens must be in good condition in order to be tested (no signs of insects or obvious injury or decay). Avoid bare-hand contact when handling any dead animal, although there is no evidence WNV infection occurs this way.



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