CDC investigates cyclosporiasis outbreak, more than 1,200 people sickened

Michigan has recorded 1,251 cyclosporiasis cases in an outbreak with no identified source, and 44 patients have been hospitalized. The cases were still climbing on July 9, extending a cluster that had already topped 170 by June 30 in a state that usually sees about 50 cyclosporiasis infections a year.

Cyclospora is spread through contaminated food or water, especially produce. Cyclosporiasis is a nationally notifiable disease, and the CDC classifies the U.S. season as May 1 through August 31, when case counts rise in spring and summer.

The CDC's July 1 surveillance update recorded 145 U.S.-acquired cyclosporiasis cases in people who became sick from May 1 through June 16 across 17 states. Twenty of those patients were hospitalized, no deaths were reported, and the agency found no evidence then of a single multistate outbreak linking all of the cases.

Michigan officials identified Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson counties as the areas where the outbreak has been concentrated, and the source has not been identified. The illness can begin two to 14 days after exposure, so patients may not connect their symptoms to a specific meal or grocery purchase until days later.

Cyclosporiasis is not known to spread person to person, and untreated illness can last from days to a month or longer. The Michigan Department of Health and Human Services says symptoms can be significantly improved with antibiotic treatment, and it urges anyone with sudden, ongoing diarrhea to contact a health-care provider.

The Michigan Department of Agriculture and Rural Development worked with local health departments to trace the source and advised careful produce handling. That includes washing produce thoroughly, washing leafy greens under running water, and, in restaurants and kitchens, preferring whole heads of lettuce over prewashed bagged mixes.