A cyclosporiasis outbreak in the United States has killed two people in Michigan and infected more than 18,000 individuals across 45 states. The intestinal infection is caused by a parasite present in contaminated lettuce.
Health authorities announced the deaths on Monday, Aug. 3. The Department of Health and Human Services stated that medical records showed both victims had significant pre-existing health conditions that may have been aggravated by cyclosporiasis and severe dehydration.
Michigan has reported 11,234 cases since the start of the outbreak, requiring 193 hospitalizations. Other smaller clusters have been declared across the rest of the country.
CDC investigation and Taco Bell link
One week ago, the Centers for Disease Control and Prevention counted more than 18,000 cyclosporiasis cases nationwide, including 6,700 confirmed cases while others remain under analysis. A total of 425 people have been hospitalized across the country.
The CDC noted an increase in cases compared to the same period in 2025. Investigators are looking into several clusters, including one linked to lettuce imported from Mexico that was used by the fast-food chain Taco Bell.
Symptoms and medical treatment
The outbreak is caused by a parasite named Cyclospora, which is found in water or fresh produce such as fruits and vegetables. After a person consumes contaminated food or water, the parasite grows in the intestine, with symptoms typically appearing two to 14 days later.
Repeated diarrhea can lead to severe dehydration. The infection can take more serious forms in vulnerable groups, including young children, elderly people, and immunocompromised patients.
While cyclosporiasis usually clears up on its own in healthy individuals, symptoms can last for several weeks and cause fatigue or weight loss. Doctors recommend a specific treatment using cotrimoxazole to eliminate the parasite.
Cases reported in the United Kingdom
Although documented in Europe, the illness is much rarer there than in the United States. According to the BBC, the UK Health Security Agency has recorded 67 cases since April, mostly among travelers returning from Mexico.
Direct human-to-human transmission of the disease is exceptional. Parasites passed in stool require several days of maturation before becoming infectious, meaning transmission occurs primarily through food or water contaminated by fecal matter containing mature parasites.
Health advice to protect against cyclosporiasis includes drinking bottled water, eating thoroughly washed and cooked food, and maintaining strict food hygiene, especially when traveling abroad.
