Expand / Collapse search
☰

'Explosive' diarrhea parasite hits Illinois as CDC searches for source

By Will Hager
FOX 32 Chicago
Health
Published July 1, 2026 10:50 AM CDT
Published July 1, 2026 10:50 AM CDT

The Brief

    • Illinois has reported several cases of cyclosporiasis, a parasitic illness that can cause severe diarrhea and other digestive symptoms.
    • Health officials are investigating the outbreak, but the source of the infections has not yet been identified.
    • The illness is most common during the spring and summer months and can last for weeks if left untreated.

CHICAGO - Illinois is reporting cases of a parasitic illness this summer that causes "explosive" diarrhea and can last for over a month.

The parasite, cyclosporiasis, infects the small intestine, typically causing watery diarrhea, and frequent, sometimes "explosive" bowel movements, according to the Centers for Disease Control and Prevention. It is spread by ingesting something — such as food or water — contaminated with feces.

Cyclosporiasis in Illinois

What we know:

The CDC says between 11 and 30 people in Illinois have been sickened by the parasite since the start of May, placing the state among those with the highest number of reported cases nationwide. Only New York and Texas have reported similar or higher case totals so far.

The CDC, along with the FDA and state health departments, is investigating several clusters of illnesses across multiple states but has not yet identified a common source.

(CDC)

Symptoms of cyclosporiasis

What you should know:

According to the CDC, the main symptoms and signs of cyclosporiasis are:

  • Watery diarrhea (most common)
  • Loss of appetite
  • Weight loss
  • Cramping
  • Bloating
  • Increased gas
  • Nausea

Less common symptoms may include vomiting, body aches, headaches and a low-grade fever.

Some people recover without treatment, but symptoms can last for weeks or even months if left untreated.

Cyclosporiasis cases typically rise during the spring and summer months, with the annual season running from May through August. 

Preventing cyclosporiasis

Dig deeper:

Health officials say the best way to avoid infection is to avoid food or water that may be contaminated with stool.

Travelers visiting areas where the parasite is more common are advised to take extra precautions, as it can survive routine chemical disinfection and sanitizing methods that are effective against some other germs. 

The CDC also notes that people can become infected more than once and develop symptoms again.

What's next:

The CDC says investigations into this year's outbreak remain ongoing.

The Source: The information in this report came from the Centers for Disease Control and Prevention.

HealthChicagoNews