First Human Case of West Nile Virus for 2016

The Illinois Department of Public Health (IDPH) has confirmed the first human case of West Nile virus reported in Illinois for 2016. An adolescent in west-central Illinois became severely ill in late May.

“We typically don’t start to see human cases of West Nile virus in Illinois until the end of July or beginning of August,” said Illinois Department of Public Health Nirav D. Shah, M.D., J.D. “This first human case is much earlier this year, reminding us that it’s important to protect ourselves against mosquito bites now and not wait until the hotter months of summer.”

Surveillance for West Nile virus in Illinois includes laboratory tests on mosquito batches, dead crows, blue jays, robins and other perching birds, as well as testing sick horses and humans with West Nile virus-like symptoms. People who observe a sick or dying crow, blue jay, robin or other perching bird should contact their local health department, which can determine if the bird will be picked up for testing.

West Nile virus is transmitted through the bite of a Culex pipiens mosquito, commonly called a house mosquito, which has picked up the virus by feeding on an infected bird. Common symptoms 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 including meningitis or encephalitis, or even death, can occur. People older than 50 and immunocompromised individuals are at higher risk for severe illness from West Nile virus.

The first bird to test positive for West Nile virus this year was collected in Arcola Township in Douglas County on May 20, 2016. The first mosquito batch to test positive for West Nile virus was collected on May 23, 2016, in Glenview.

IDPH reported the first human case of West Nile virus last year on August 19, 2015. Last year, 64 counties in Illinois reported a West Nile virus positive mosquito batch, bird and/or human case. For the 2015 season, IDPH reported 77 human cases (although human cases are underreported), including nine deaths.

While Zika virus is also primarily transmitted through the bite of a mosquito, the main type of mosquito that carries Zika virus, Aedes aegypti, is different and is rarely found in Illinois. However, taking some simple precautions can help you avoid mosquito bites, regardless of the type of mosquito or the diseases they carry.

Precautions include 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 long-sleeved shirt, and apply insect repellent that contains DEET, picaridin, oil of lemon eucalyptus, or IR 3535 according to label instructions. Consult a physician before using repellents on infants.

• 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 eggs.

Additional information about West Nile virus can be found on the IDPH website.