Chicago reports first 3 human cases of West Nile virus in 2025
Chicago public health officials on Tuesday confirmed the city's first three human cases of West Nile virus in 2025.
Chicago Department of Public Health officials said all three people began experiencing symptoms of the mosquito-borne virus in late July or early August. Their ages range from 40 to 80 years old.
The state's first human case of West Nile virus was confirmed in late June in southern Illinois, the earliest a human case of the virus has been confirmed in the state since 2016.
Human cases also have been confirmed in Lake and DuPage counties so far this summer.
Public health officials said a larger proportion of mosquitos has tested positive for tWest Nile virus than usual this year, increasing the risk for humans to contract the virus, which is primarily spread through bites from infected mosquitos, and generally not spread from person to person.
"The best way to protect yourself from West Nile virus is to avoid mosquito bites and take measures to stop them from breeding around your home," said CDPH Commissioner Dr. Olusimbo 'Simbo' Ige.
What is West Nile virus? How to prevent it.
West Nile virus is spread to people from infected mosquitoes, most commonly in the summer. Eight out of 10 people infected do not develop symptoms, according to the CDC.
The public is advised to do their best to protect themselves from mosquito bites, including using an EPA-registered insect repellent, wearing loose-fitting clothing, and, if possible, avoiding peak mosquito feeding times, typically around dusk and dawn.
"As the weather gets warmer, all Chicago residents are encouraged to Fight the Bite and protect themselves against mosquito bites so they can remain safe and healthy this summer," CDPH Commissioner Dr. Olusimbo Ige said.
It is also encouraged to check often overlooked places that may contain water, such as bird baths, water pails, and flower pots.
What are the symptoms of West Nile virus?
While most people infected with the virus do not feel sick, about one in five will develop a fever and flu-like symptoms. Other symptoms include body aches, vomiting, diarrhea, or rash.
Severe illness can occur in about one in 150 people and is most likely to occur in people over age 55 or with weakened immune systems.
The department said there are no specific medications to treat the virus in people. The best way to prevent getting sick is to prevent mosquito bites.