CHICAGO – The Illinois Department of Public Health (IDPH) announced the first 2024 death of an Illinois resident with West Nile virus (WNV). The individual, who was in their 80’s and lived in Lake County, had an onset of symptoms of WNV in mid-August and died soon after. IDPH is also reporting nine non-fatal cases of WNV confirmed to date this year.
“Sadly, Illinois is reporting our first death of the year attributed to West Nile virus,” said IDPH Director Dr. Sameer Vohra. “This death – and the six that occurred last year in Illinois – are a stark reminder that West Nile virus poses a serious risk, especially to older people and those with weakened immune systems. This is why while warm weather continues and mosquitoes are breeding, we should all take steps to ‘Fight the Bite.’ Please protect yourself and your loved ones by reducing exposures, repelling insects with clothing and repellents, and reporting locations at high risk for producing mosquitoes.”
Of the nine other human cases in 2024 to date, the majority were reported from Cook County, with others in in DuPage, Will, Winnebago and Tazewell counties.
The first WNV-related death in Illinois in 2023 also had an onset of symptoms in August. There were six deaths from WNV confirmed in the state in 2023 and an additional 119 non-fatal cases reported (although human cases are underreported). The youngest person to report a case of West Nile virus in Illinois last year was 33 years old, while the median age of human cases was 67.
West Nile virus is transmitted through the bite of a Culex mosquito, commonly called a typical mosquito, which has picked up the virus by feeding on an infected bird. Common symptoms of WNV include fever, nausea, headache and muscle aches. Symptoms may last from a few days to a few weeks. Four out of five people infected with West Nile virus will not show any symptoms. However, in rare cases, severe illness can occur, including brain infections such as meningitis or encephalitis and paralysis or even death. People older than 50 and immunocompromised individuals are at higher risk for severe illness from West Nile virus.
There is no specific treatment for WNV nor is there a vaccine at present, therefore it is critically important that people minimize their risk of being infected by it.
IDPH encourages the public to Fight the Bite and take steps to prevent WNV by practicing the three “R’s” – reduce, repel, and report:
- REDUCE – make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut.
Eliminate, or refresh each week, all sources of standing water where mosquitoes can breed, including water in bird baths, ponds, flowerpots, wading pools, old tires, and any other containers.
- REPEL -when outdoors, wear shoes and socks, long pants and a light-colored, long-sleeved shirt, and apply an EPA-registered insect repellent that contains DEET, picaridin, oil of lemon eucalyptus, or IR 3535 according to label instructions. The CDC does not recommend use of products containing oil of lemon eucalyptus or para-menthane-diol on children under 3. Consult a physician before using repellents on children under 3.
- REPORT – report locations where you see water sitting stagnant for more than a week such as roadside ditches, flooded yards, and similar locations that may produce mosquitoes. The local health department or city government may be able to add larvicide to the water, which will kill any mosquito larvae.
Last year, 67 counties in Illinois reported positive WNV mosquitoes, birds, humans and/or horses. So far in 2024, there have been 2,113 positive mosquito batches, 29 positive birds, and one positive horse from 57 counties. This year, the first mosquito batches to test positive for WNV were reported May 14 in Cook and Morgan Counties.
Surveillance for West Nile virus in Illinois involves reporting and investigation of individuals with West Nile virus symptoms and clinical laboratory testing. Environmental surveillance includes laboratory testing on mosquito batches, dead birds, as well as testing sick horses. People who observe a sick or dying bird should contact their local health department, which can determine if the bird will be picked up for testing.
Additional information and data on WNV in Illinois can be found at: West Nile virus.