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Recently, headlines about an outbreak causing so-called “explosive diarrhea” have drawn attention. While that phrase can sound offhand, this Cyclospora parasite outbreak is a real public-health problem. It started in the United States and has now reached European shores, triggering an alert in the United Kingdom. The situation has been developing for several weeks and raises questions about food safety and international travel.
U.S. Outbreak Widens
The outbreak of cyclosporiasis has been linked to the first two deaths in the United States, with fatalities reported in Michigan. Those individuals had pre-existing health conditions that were worsened by cyclosporiasis and dehydration.
The Centers for Disease Control and Prevention (CDC) reported that as of late July 2026, more than 18,000 people might have been infected across 45 states, with 423 hospitalizations. Laboratory-confirmed cases top 6,700. The states hit hardest include Michigan and Ohio, and investigations have tied some contamination to lettuce from a Mexican supplier that was used by Taco Bell.
The American Medical Association also noted that Cyclospora can’t be grown in labs, which makes diagnosis and research harder. The CDC warns that symptoms such as fever, nausea, and “explosive diarrhea” are usually not fatal but can last untreated from a few days up to one month, causing severe dehydration.
Across the Atlantic: What’s Happening in the U.K.
The UK Health Security Agency (UKHSA) has logged 67 cases between April and July 2026, illustrating how the pathogen can move regionally via infected travelers. U.K. public-health officials are monitoring the situation to try to prevent a large-scale outbreak similar to the one in the United States.
Professor Jennifer Horney from the University of Delaware says the disease does not spread directly from person to person. It is passed mainly through contaminated food and water, often linked to produce that has not been washed well or that was exposed to fecal matter containing oocysts (oocysts are the parasite’s reproductive structures). Cases tend to rise in summer when conditions favor the parasite, so strict food-handling practices are important.
Tracing the Source: What Investigations Found
Investigators from an unnamed federal food-safety agency in the United States identified lettuce used by Taco Bell in five states as a major vehicle for the contamination. That lettuce, which came from a Mexican supplier, was implicated in spreading the outbreak.
Those findings have pointed to gaps in supply-chain safety and suggest stricter protocols may be needed in food importation practices to prevent similar events in the future.
The CDC continues to issue guidance and to support state health departments as they respond. With the number of suspected cases exceeding 11,500, officials are focused on containing spread, raising public awareness, and tightening food-safety measures across the supply chain. The CDC is providing coordinating support for public-health actions in this transcontinental outbreak.
The spread of Cyclospora across borders shows how interconnected global health and food systems are and underscores the need for vigilance and international cooperation. As health agencies work to contain the infection, maintaining public-health infrastructure and following established food-safety policies are central to protecting communities.
