Michigan's diarrheal parasite outbreak surpasses 700 cases in two weeks

Michigan has reported over 700 cases of a diarrheal parasite outbreak, with the Michigan Department of Health and Human Services (MDHSS) confirming the surge on July 6. The outbreak, which began on June 22, has led to 36 hospitalizations and remains without a clear source.

Understanding Cyclospora and Its Effects

The outbreak is attributed to the microscopic unicellular parasite Cyclospora cayetanensis, which causes a disease known as cyclosporiasis. Symptoms typically include watery and explosive diarrhea, which can last from a week to over two weeks. According to the Centers for Disease Control and Prevention (CDC), dehydration is a significant concern for those infected.

The parasite is primarily spread through contaminated food and water. It is shed in feces and can contaminate produce, emphasizing the importance of thorough washing and hand hygiene as preventive measures.

Investigation into the Outbreak Source

Despite the rising case numbers, MDHSS has not yet identified a specific source or type of produce linked to the outbreak. Past outbreaks have been connected to items like bagged salad mixes, cilantro, and raspberries. Currently, the state is coordinating a comprehensive investigation with local health departments in southeastern Michigan, where most cases have been reported.

Officials are actively interviewing affected individuals and gathering data to find common exposures. MDHSS is also in collaboration with the CDC and has shared the latest case data, although the CDC's surveillance website has not been updated to reflect Michigan's recent cases.

National Context and Historical Trends

This surge in Michigan's cases is notable, especially when compared to the state’s historical trends, which typically report around 50 cases annually. In fact, the state recorded only 97 cases in 2023 prior to this outbreak. The nationwide context shows that the CDC has reported cases from 17 other states, totaling 145 cases this year, bringing the national tally to over 845 when including Michigan.

Historically, the U.S. has seen between 2,000 and 5,000 cases of cyclosporiasis each year. The CDC’s latest figures show 4,463 cases reported in 2023, indicating that while Michigan is experiencing a record outbreak, national trends appear consistent with previous years.