A Parasite Outbreak Has Sickened Over 300 Michigan Residents and Is Still Growing

A Rapid Surge No One Saw Coming

Michigan is working to identify the cause of a "sudden and large" increase in an infection that causes gastrointestinal issues and has sickened more than four times as many residents in just ten days as the state normally experiences in an entire year. The illness is cyclosporiasis — a parasitic infection most people have never heard of — and it is spreading fast across southeast Michigan heading into the Fourth of July holiday weekend.

On July 1, state health officials reported at least 170 cases. By Thursday, July 3, that number had jumped to at least 300. Typically, Michigan only identifies around 50 cyclosporiasis cases per year. To go from a manageable annual baseline to 300-plus confirmed cases in roughly ten days has public health officials alarmed — and bracing for more.

Wayne County at the Center of a Wider Crisis

Wayne County health officials say they are tracking 27 potential cases of cyclosporiasis as part of the growing intestinal illness outbreak spreading across southeast Michigan. The cases have chiefly been found in Monroe, Washtenaw, Wayne, Livingston, Shiawassee, Lenawee, and Jackson counties, but have spread across 21 counties in total. Monroe County has been hit hardest: 92 cases of the illness were reported there alone since June 22.

The age range of individuals diagnosed with the illness spans from 8 years old to 84 years old, with a median age of 41. This is not an illness targeting one demographic — it is cutting across all age groups. Just south of Monroe and Lenawee counties, the Toledo-Lucas County Health Department in Ohio also reported a recent increase in the intestinal illness. The outbreak is not staying neatly within state lines.

What Cyclosporiasis Actually Does to the Body

Cyclosporiasis is an intestinal illness caused by the parasite Cyclospora cayetanensis. It spreads through food or water contaminated with the parasite and is not typically transmitted from person to person. That last point is important: you cannot catch it from a sick family member or coworker. But you could pick it up from contaminated produce without knowing it.

The infection can cause "watery diarrhea with frequent and sometimes explosive bowel movements" and, without antibiotics, may last from a few days to more than a month. Symptoms can relapse, and the timeframe from becoming infected to becoming sick usually takes about one week, but can range from two days to two weeks or more. One Michigan resident who tested positive described being completely bedridden. "I could not function on Thursday or Friday. I mean, there was no getting out of bed. I mean, I slept all day on Thursday and Friday," she said. Symptoms of cyclosporiasis can be significantly improved with antibiotic treatment.

No Source Found Yet — Here's What You Can Do

Wayne County Public Health is collaborating with the Michigan Department of Health and Human Services, the Michigan Department of Agriculture and Rural Development, and local health departments to investigate the outbreak. The Centers for Disease Control and Prevention is also investigating the source of a cyclosporiasis outbreak it said sickened at least 145 people in 17 states. Despite the scale of the investigation, no food source has been pinpointed.

While investigators work to identify a point of common exposure, officials say all produce needs to be thoroughly washed, whether in a restaurant or at home. The CDC urges thorough washing of fruits and vegetables under running water and scrubbing firm produce. Michigan's chief medical executive warned that additional cases are anticipated, recommending that residents contact their health care provider if they experience sudden, ongoing diarrhea and reach out to their local health department if additional family members show the same symptoms. With the source still unknown and case counts still climbing, that advice is worth taking seriously — especially as millions gather for holiday cookouts today.