Michigan Reports 992 Cyclospora Cases, Largest Outbreak on Record, With No Deaths

Michigan has recorded 992 cases of cyclospora infection as of Wednesday, marking the largest such outbreak in state history. About 40 people have been hospitalized, though no deaths have occurred. State officials first announced the outbreak last week after identifying more than 170 cases since June 22, all concentrated in the southeastern corner of Michigan.

The state normally sees about 50 cases annually. Lucas County, Ohio, reported 306 cases as of Wednesday, while northwest Ohio has recorded more than 500. Investigations into similar illnesses continue in 28 other states.

"There is clearly a linked outbreak happening right now," Dr. Natasha Bagdasarian, Michigan’s chief medical executive, said Wednesday. The current U.S. cyclospora total stands four times higher than at the same point last year, according to CDC data.

Dianna Blau, the CDC’s acting parasitic diseases branch chief, stated there is no evidence the parasite has evolved to become more infectious. Cyclospora is a microscopic parasite that causes watery diarrhea with frequent and sometimes explosive bowel movements. The resulting cyclosporiasis is typically treated with antibiotics and is not usually life threatening.

Outbreaks occur most often in late spring and summer. The source of the current infections has not been identified. Officials recommend washing fresh produce thoroughly, purchasing whole heads of lettuce rather than prewashed mixes, and cooking vegetables when possible.