Michigan Cyclosporiasis Outbreak Passes 7,000 Cases as Source Remains Unknown

Michigan health officials said Wednesday that 7,171 people have fallen ill with cyclosporiasis since June 22, up from 6,571 a day earlier, in an outbreak whose source has not been identified. The Michigan Department of Health and Human Services (MDHHS) reported the totals, according to WDIV in Detroit.

Cyclosporiasis is an intestinal infection caused by the parasite Cyclospora cayetanensis, which spreads when food or water is contaminated with infected feces, CBS News Detroit reported. Symptoms usually begin about a week after infection and include frequent watery diarrhea, loss of appetite, bloating, nausea and fatigue. Wayne County health officials warned that without treatment, illness can last for weeks and may come and go.

The outbreak is far outside normal experience. Michigan typically sees about 50 cases a year, CBS News Detroit reported, so the current count is more than 100 times a typical year’s total, though this report covers a single summer’s cases. WDIV said 102 people had been hospitalized as of July 16, and neither outlet reported any deaths. WDIV listed Monroe, Lenawee, Washtenaw and Wayne among the counties with the highest counts; Monroe County officials first identified the outbreak in late June, per CBS News Detroit.

Investigators have not found the source. On July 13, Michigan officials said testing pointed to lettuce or salad greens as a potential source, though other foods were not ruled out, CBS News Detroit reported. On Sunday, July 19, the FDA said a Taylor Farms iceberg lettuce sample from central Mexico that had tested positive for the parasite was a false positive. The investigation remains open. Foods previously linked to Cyclospora outbreaks include bagged salad mixes, fresh cilantro, fresh basil, raspberries, snow peas and green onions, WDIV noted.

The CDC has identified cases in 34 states and expects illnesses to keep rising through the end of August, when the typical Cyclospora season ends, WDIV reported. The CDC is working with the FDA and state authorities on multiple clusters, CBS News Detroit reported.

MDHHS guidance, as relayed by WDIV, advises people with ongoing diarrhea or other stomach illness to contact a health care provider and their local health department. The department suggests buying whole heads of lettuce rather than bagged or pre-mixed salads, discarding outer leaves and washing the inner ones, and cooking greens to at least 158 degrees Fahrenheit. It urges extra caution for people with weakened immune systems, young children and older adults.

Health Secretary Robert F. Kennedy Jr. said on July 21 that the outbreak is under control and denied that cutbacks in monitoring have hurt U.S. food safety, CBS News Detroit reported. The case counts are updated Monday through Friday, so the totals will keep changing as more reports arrive.

Reported counts reflect people who sought care and were tested or reported, so the true number of infections may be higher. The outlets do not cite an independent epidemiologist’s assessment of the outbreak’s size.