Thousands of people across 34 U.S. states are experiencing an outbreak of cyclosporiasis, a parasitic illness causing severe and prolonged diarrhea. Health officials have linked the outbreak to contaminated food products, prompting a voluntary recall by Taylor Farms of iceberg lettuce sourced from central Mexico. The recall, announced on Friday, affects products distributed to at least 27 states, including Texas, Florida, Pennsylvania, Illinois, and New Jersey.

Michigan has emerged as the epicenter of this outbreak, with more than 3,700 reported cases. Public health investigators are focusing on leafy greens as a possible source of the parasite. In Michigan, some Taco Bell locations have temporarily halted sales of lettuce, cilantro, onion, pico de gallo, and guacamole due to the nationwide recall linked to the outbreak.

Although the majority of cases are concentrated in the Midwest and East Coast, experts are advising caution nationwide, including in California, where 41 cases have been reported from January to June. These cases, however, are not related to the current outbreak and fall within the state’s usual annual range, which averages around 100 cases mostly acquired through international travel, according to the California Department of Public Health.

Cyclosporiasis outbreaks in the United States have historically been associated with fresh produce imported from Latin America, such as raspberries, cilantro, basil, snow peas, and mixed salads. Previously, a major outbreak in 1996 involved imported raspberries from Guatemala, resulting in over 1,400 illnesses across multiple states and Canada.

To mitigate the risk of infection, health officials recommend thorough handwashing with soap and water before handling produce, washing all fruits and vegetables under running water, removing outer leaves from leafy greens, and cooking vegetables and herbs when possible—especially for vulnerable groups including children, pregnant women, and immunocompromised individuals. Additional precautions include preventing cross-contamination by using clean utensils and surfaces and refrigerating cut or cooked produce promptly.

Experts caution that while rinsing is important, it may not completely eliminate the parasite because of its tough outer shell, which resists environmental pressures and traditional disinfectants. The parasite is typically found in soil and can contaminate produce through contact with contaminated water or inadequate hygiene among handlers. Some specialists advise extra caution with bagged leafy greens, particularly in outbreak-affected areas, recommending that consumers either avoid these products or cook them thoroughly.

This parasite produces symptoms such as watery diarrhea lasting for up to a week, loss of appetite, cramping, nausea, and fatigue. Those experiencing severe symptoms are encouraged to seek medical attention. Diagnosis commonly involves stool testing, and treatment usually includes a prescribed antibiotic, typically Bactrim.

Officials emphasize that the outbreak will persist until the specific contaminated source is conclusively identified. Once confirmed, targeted recalls can effectively limit further spread. Until then, heightened vigilance in food handling and preparation remains crucial.