Explosive cyclosporiasis surge hits Michigan; CDC tracks spread

explosive cyclosporiasis – Cyclosporiasis, a parasitic infection that can cause sudden, watery “explosive” diarrhea, is rising across the United States—most sharply in southeast Michigan. Since June 22, 2026, more than 170 cases have been reported in multiple Michigan counties, health o

The first warning signs can be quick and brutal: severe, watery diarrhea that hits fast enough to feel uncontrollable. In southeast Michigan. health officials are seeing that kind of illness spread far more widely than the state typically detects—pushing both local teams and federal investigators to hunt for a source.

Michigan officials say a “sudden and large” increase in cyclosporiasis cases began showing up. and they have been moving with urgency ever since. Since June 22, 2026, more than 170 cases of cyclosporiasis have been reported in southeast Michigan—up from 150 several days prior. That jump is out of the norm for the state. “Michigan typically identifies 50 cases a year,” a spokesperson for the Michigan Department of Health and Human Services said.

The illness is caused by a microscopic parasite, Cyclospora cayetanensis, and it spreads through contaminated food or water through the fecal-oral route. In this current surge, officials have not identified the source so far.

Across the country, the pattern is also widening. The U.S. Centers for Disease Control and Prevention says cyclosporiasis cases have been on the rise in multiple states since May. The most recent CDC data shows at least 145 cases of cyclosporiasis were reported in 17 U.S. states between May 1 and June 16. That dataset does not include the recent increase in Michigan.

Nationwide so far, at least 20 people have been hospitalized, and no deaths have been reported. The CDC says the “true number of people sick with cyclosporiasis was likely higher than the number reported.”

New York has reported the highest number of cases, followed by Illinois and Texas, according to the CDC. The infected range in age runs from 5 to 86 years old.

Michigan’s investigation is now focused on where the cases are concentrated. More than 170 cases have been reported since last week across seven counties in Michigan: Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson.

The CDC is working with the U.S. Food and Drug Administration and local officials to investigate clusters in multiple states. The agency says those infected became sick after eating food in the U.S., and none reported traveling in the weeks prior. It remains unclear whether the clusters are related.

Cyclosporiasis is seasonal in the U.S., and cases typically peak between May and August, per the CDC. Health officials say increases during summer months can happen—but the latest spike in Michigan has them on high alert and urging people to seek care if they experience symptoms.

The symptoms can be severe and disruptive. After ingesting the cyclospora parasite, it takes anywhere from two to 14 days to show signs of illness. The main symptom is severe, watery “explosive” diarrhea. People who get infected may also experience appetite loss. stomach cramps. nausea. vomiting and a low-grade fever. according to the Cleveland Clinic.

The illness can last for a few days to over a month or longer. Symptoms may come in waves and return more than once after going away, known as “relapses,” per the CDC. The infection is typically treated with a combination antibiotic. though the CDC says most people with healthy immune systems will recover on their own. Individuals with weak immune systems are at higher risk for prolonged illness and relapses.

The CDC says people who experience cyclosporiasis symptoms or severe, sudden gastrointestinal illness should contact their health care provider. If someone tests positive for the parasite, the CDC advises contacting the local health department.

The investigation is also being steered by what the parasite is known to do in past outbreaks. In the U.S. cyclosporiasis outbreaks have been linked to fresh fruits and vegetables. including basil. cilantro. raspberries and snow peas. per the CDC. The CDC says the parasite usually takes one to two weeks outside the body to become infectious. making human-to-human transmission highly unlikely.

Keeping that timeline in mind matters now, because it helps explain why investigators are emphasizing food safety and exposure. The CDC notes that cyclosporiasis outbreaks are tied to contaminated produce and urges prevention by avoiding food or water that may be contaminated with feces.

In recent years, the number of infections reported in the U.S. has increased significantly. In 2019, an unusually high number of cyclosporiasis infections (4,703) were identified, according to a 2023 report from the CDC. The current surge arrives after a year-round expectation of several hundred cases annually. according to the CDC—making this stretch of new illnesses more urgent to contain.

For now, the source in Michigan remains unidentified. But the timing and scale of the increase—beginning in late June and expanding quickly across multiple counties—has turned what is usually a seasonal illness into a fast-moving public health problem.

cyclosporiasis Cyclospora cayetanensis explosive diarrhea CDC Michigan southeast Michigan foodborne illness fresh produce hospitalization