Summary (tl;dr)

A parasitic outbreak causing severe gastrointestinal illness, identified as cyclosporiasis, is currently spreading across at least 17 states in the U.S., sickening 145 people with an additional 150+ cases reported in specific Michigan counties.

Essential Background

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. People become infected by consuming food or water contaminated with the parasite, which typically causes watery and often "explosive" diarrhea, along with other symptoms like loss of appetite, bloating, fatigue, nausea, and stomach cramps. The illness is nationally notifiable, meaning healthcare providers are required to report cases to federal authorities, and outbreaks commonly occur in the spring and summer months in the U.S.

The Full Story

Health officials, including the CDC, are actively investigating a multi-state outbreak of cyclosporiasis that has affected 145 individuals across at least 17 U.S. states between May 1 and June 16, 2026. Twenty people have been hospitalized due to the infection, though no deaths have been reported in this specific outbreak. The infections are believed to be linked to contaminated food consumed within the United States, as none of the affected individuals reported recent international travel. Investigations to identify the exact source of contamination are ongoing. Separately, Michigan health officials are investigating a distinct cyclosporiasis outbreak with over 150 reported cases across several Southeast Michigan counties since June 22.

Why It Matters

This outbreak is significant because the source of the contaminated food has not yet been identified, posing an ongoing risk to the public. Cyclosporiasis symptoms can be severe and prolonged, lasting from several days to a month or more, and can relapse if left untreated, potentially leading to dehydration and malnutrition. While most healthy individuals recover, treatment with antibiotics is often recommended, especially given the "explosive" nature of the diarrhea. Previous U.S. outbreaks have often been linked to imported fresh produce such as cilantro, raspberries, sweet peas, mesclun lettuce, and basil.

Geographic Location

• New York, United States (highest concentration of cyclosporiasis cases in multi-state outbreak)
• Illinois, United States (reported cases of cyclosporiasis in multi-state outbreak)
• Texas, United States (reported cases of cyclosporiasis in multi-state outbreak)
• Monroe County, Michigan, United States (local investigation into cyclosporiasis outbreak with 67 reported cases)
• Wayne County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)
• Washtenaw County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)
• Lenawee County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)
• Livingston County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)
• Shiawassee County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)
• Jackson County, Michigan, United States (reported cases of cyclosporiasis in local outbreak)