1st human case of West Nile virus recorded in McHenry County; only 3rd known case in last 5 years

The first human case of West Nile virus of 2024 has been reported by the McHenry County Department of Health.

Eight batches of mosquitos have tested positive for the virus as of Sept. 6, as well as one owl, in the county. Statewide, 19 human cases have been confirmed this year, including one death, according to the Illinois Department of Public Health.

The McHenry County health department said there are only two other known cases in the county in the past five years, in July 2022 and September 2023.

In humans, illness typically occurs two days to two weeks after the bite of an infected Culex mosquito, although most people exposed don’t develop symptoms, possibly because past exposure has given them immunity, the health department says. It cautions that about 20% of those infected experience mild fever along with other possible symptoms like headaches, body aches, joint pains, vomiting or a rash.

“Severe symptoms are very rare and include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. Individuals 60 years of age or older or those with serious underlying health conditions, such as diabetes, kidney disease, hypertension, cancer, or who have received organ transplants are at greater risk for developing severe symptoms,” according to the McHenry County health department release.

The McHenry County health department also says:

There is no vaccine or treatment for WNV. Mild symptoms can be relieved with rest, fluids, and over-the-counter medications for pain and fever. Seek medical attention if you or an individual you know develops severe symptoms.

People should try to protect themselves from mosquito-borne illnesses. Culex mosquitoes typically breed in stagnant water with high organic content, often found in artificial containers like rimless tires, abandoned swimming pools, buckets, bird baths and clogged gutters. “The first and best defense against mosquito-borne illness is to eliminate potential mosquito breeding sites on your property by emptying standing water from containers around your home and ensuring doors and windows have tight-fitting screens.”

When outdoors, wear long-sleeved shirts, pants, shoes, and socks, especially during dawn and dusk when Culex mosquitoes are most active. Use EPA-registered insect repellents with one of the following active ingredients, and apply them according to label directions: DEET (N,N-diethyl-meta-toluamide), picaridin (KBR 3023); IR3535 (a biopesticide), oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone. Consult with a doctor before using any repellent on infants.

For more on West Nile virus, go to mcdh.info or call 815-334-4510.