Michigan cyclosporiasis case count now tops 2,600. Why CDC data is lagging
Michigan's outbreak of cyclosporiasis, a gastrointestinal parasite that causes watery, sometimes explosive diarrhea, reached a new threshold Monday, July 13, growing by nearly 1,000 cases over the weekend.
The number of people who've been sickened by the parasite since June 22 now totals 2,640, the Michigan Department of Health and Human Services reported. Other states also are reporting growing outbreaks of illness caused by a tiny, single-celled parasite called Cyclospora cayetanensis, but none appear to have as many people sickened by it as Michigan, reports the Detroit Free Press, which is a part of the USA TODAY Network.
The Centers for Disease Control and Prevention reported 843 cases nationally between May 1 and July 10, acknowledging that its totals are lagging compared with case counts from local and state health departments. Health experts have warned previous cuts to food surveillance could hinder the outbreak investigation.
"So far this year, multiple states have reported an increase in cases in the last two weeks compared to the same period in 2025," the CDC said on its cyclosporiasis surveillance website. "State and federal partners are working together to investigate several outbreaks of cyclosporiasis. Investigations to identify source(s) of illness are ongoing."
Cyclospora is a protozoan parasite that is so small, it can only be seen with a microscope. It can infect humans when they eat food or drink water that has been contaminated with fecal matter.
The parasite generally does not spread directly from person to person because of its lifecycle, said Dr. Rebecca Schein, a pediatric infectious disease specialist at the University of Michigan Health-Sparrow in Lansing, who spoke to the Detroit Free Press for a previous story.
It can take days to weeks after being passed in an infected person's poop to become infectious to another person when they ingest food or water that has been tainted by contaminated feces.
The source of the outbreak has not been identified, and MDHHS said it is continuing to work with local health departments and other agencies to investigate.
As of July 9, 44 people in Michigan reported they had been hospitalized with cyclosporiasis infections in this outbreak, the health department reported.
Contact Kristen Shamus: kshamus@freepress.com. Subscribe to the Detroit Free Press.
This article originally appeared on Detroit Free Press: Michigan cyclosporiasis case count now tops 2,600. Why CDC data is lagging
Reporting by Kristen Jordan Shamus, Detroit Free Press / Detroit Free Press
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This story was originally published July 13, 2026 at 12:47 PM.