“Explosive” diarrhea parasite infections soar in Michigan

Hundreds of people across several states have been infected by a microscopic parasite that causes severe diarrhea and vomiting, part of a multi-state surge in illness clusters that federal and local health officials are actively investigating.

The Centers for Disease Control and Prevention (CDC) reported this week that at least 145 cases of cyclosporiasis were confirmed nationwide between May 1 and June 16, resulting in at least 20 hospitalizations. However, localized data indicates the actual number of infections is significantly higher than the initial federal tally, with at least 18 states now reporting cases.

Michigan has emerged as a major hotspot for the infection. The Michigan Department of Health and Human Services (MDHHS) announced it is managing a “large and growing outbreak,” confirming to ABC News that more than 300 cases have been identified in the state as of Thursday. Michigan typically records only about 50 cases of cyclosporiasis per year.

The outbreak is heavily concentrated in Southeast and Southern Michigan, with Monroe County tracking the highest number of infections, the Detroit Free Press reported earlier this week. Significant clusters have also been reported in Lenawee, Washtenaw, Wayne, Livingston, Shiawassee, and Jackson counties, as well as the city of Detroit.

“Outbreaks of cyclosporiasis have been occurring across the United States and now here in Michigan,” Dr. Natasha Bagdasarian, the state’s chief medical executive, said in a statement. “Based on the unusual number of cases we have identified in a little over a week, we anticipate additional cases of illness being reported.”

In New York, health officials have tracked 107 cases since early May, according to local reports.

Newsweek contacted MDHHS and the CDC on Saturday morning via email and online form for comment.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. According to the CDC, the parasite is spread when people consume food or water contaminated with infected feces.

Symptoms can take up to two weeks to appear and are often flu-like, including nausea, abdominal cramps, fatigue, and bouts of watery, sometimes explosive diarrhea.

While healthy individuals typically recover without medical intervention, health officials warn that vulnerable populations, including older adults, face a higher risk of severe or prolonged illness. The infection is not passed directly from person to person.

The CDC notes that the disease can be treated with a combination antibiotic regimen of trimethoprim-sulfamethoxazole, commonly sold under the brand names Bactrim, Septra, or Cotrim. Public health officials also emphasize the importance of rest and fluid intake to prevent dehydration from diarrhea.

Where Are the Cases?

Federal health officials say there is currently no evidence linking all cases to a single source, suggesting instead that multiple regional clusters may be occurring simultaneously.

Michigan, New York, Illinois, and Texas have reported the highest concentrations of the illness. Other states identifying cases include Alaska, Colorado, Connecticut, Florida, Georgia, Louisiana, Massachusetts, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, and Wisconsin.

According to the CDC, none of those who became sick before June 16 reported any travel in the two weeks before their illness.

The agency says that past outbreaks have been linked “to various types of imported fresh produce, including raspberries, basil, snow peas, mesclun lettuce, and cilantro.” The CDC is cooperating with the U.S. Food and Drug Administration (FDA) and local health agencies like the Michigan Department of Agriculture and Rural Development (MDARD) to determine the origin of the recent regional clusters.

“MDARD is committed to ensuring food safety across the state and is working in partnership with local health departments to identify the source of the outbreak and keep consumers safe,” Jennifer Bonsky, Director of the Human Food Division at MDARD, said. “In these moments, it becomes even more important to follow all of the essential food preparation guidelines, such as washing your hands before and after preparing food and washing produce before it is consumed.”

Contact Newsweek editors for this story: Matthew Robinson and Anthony Murray.