Cyclospora Outbreak Infects >1,500 in Michigan, Spreads to 31 US States

As of July 10 2026, Michigan’s health department has confirmed 1,562 cases of cyclosporiasis, a parasitic intestinal infection caused by Cyclospora cayetanensis, with 44 hospitalizations and no deaths. The outbreak, the largest in the state’s history, has spread to at least 31 U.S. states, with the CDC reporting over 2,800 confirmed cases in 32 states and more than 1,500 additional suspected cases under investigation.

The source of the contamination remains unknown; investigators have not identified a specific produce item, grower, or supplier. Symptoms typically include watery, “explosive” diarrhea, nausea, abdominal cramping and fatigue, lasting from days to several weeks if untreated. The CDC recommends thorough washing of fresh fruits and vegetables, removal of damaged portions, and cooking at temperatures above 70 °C. It also advises avoiding pre‑washed, bagged lettuce and salad mixes where possible.

State health officials, the CDC and the FDA are conducting whole‑genome sequencing of parasite isolates and epidemiological traceback to locate the source. While the illness is usually non‑fatal, dehydration can be a serious complication, especially for vulnerable populations. No fatalities have been reported to date.