Downstate mosquitoes first to test positive for West Nile virus in 2015

A batch of downstate mosquitoes were Illinois’ first to test positive for West Nile virus this year.

Authorities found the infected mosquitoes on Tuesday in O’Fallon, about 20 miles southeast of St. Louis, according to a statement from the Illinois Department of Public Health. No human cases have been reported this year.

“West Nile virus activity is largely dependent on the weather and with the increased temperatures we’ve been seeing in Southern Illinois, mosquitoes carrying West Nile virus are becoming active,” said IDPH Director Nirav D. Shah.

The virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird, leading to fever, nausea, headache and muscle aches, officials said. Infected patients sometimes may not show symptoms of the disease, which can lead to death.

The first West Nile batch of the 2014 was reported about the same time of year, with health officials reporting 44 human cases total in Illinois, including four deaths, by the end of the year.

Officials urge people to wear insect repellent, dispose of any standing water around their homes and report dead animals to health department authorities.