Outbreak of diarrhea-causing parasite grows to more than 1,000 cases
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- Michigan health officials reported 992 cyclospora cases as of Wednesday, including about 40 hospitalizations — the largest such outbreak in state history, up from 170+ cases announced just last week since June 22.
- Investigations span 28 other states, with Lucas County, Ohio reporting 306 cases and northwest Ohio tallying more than 500; Michigan normally identifies only about 50 cases per year.
- The source of infection remains unidentified because cyclospora is notoriously hard to trace — technicians can't grow the parasite in labs, and contaminated food may reach both grocery stores and restaurants through shared distributors.
- The current case total is four times higher than at the same point last year, per CDC national data, though acting parasitic diseases branch chief Dianna Blau said there's no evidence the parasite has evolved to become more infectious.
- Only a handful of documented U.S. outbreaks have surpassed 1,000 cases — a 1997 outbreak tied to Guatemalan raspberries (1,000+ sickened) and a 2019 outbreak linked to Mexican basil (2,400+ sickened).
- Michigan's chief medical executive Dr. Natasha Bagdasarian said the state's aggressive case-finding may be "part of the reason why this looks like a Michigan problem," noting reporting lags in national CDC data.
- Officials recommend consumers buy whole heads of lettuce instead of prewashed bagged mixes, strip the outer two to three leaves, and cook vegetables when possible — washing alone may not eliminate the parasite.
Why it matters: For consumers in Michigan and Ohio, the practical reality is that no contaminated food has been recalled or identified weeks into the outbreak, so prevention advice has shifted to produce handling — whole lettuce over prewashed bags and cooking vegetables. The ~40 hospitalizations and 4x year-over-year case jump put this in rare U.S. territory: only two documented outbreaks in the past 25 years have exceeded 1,000 cases.
