Michigan health officials are racing to find the source of a cyclosporiasis outbreak that has sickened people in at least 33 states — and the extreme heat sweeping across the region is adding another layer of risk.
The illness, caused by the parasite cyclospora, has been confirmed in 3,762 people in Michigan as of today, according to the Michigan Department of Health and Human Services.
The state has more confirmed cases than any other in the country, putting Michigan at the center of the effort to identify the outbreak’s source.
Cyclospora is typically spread by eating fruits or vegetables contaminated with human feces. The illness can cause severe, watery diarrhea, and the greatest health concern is dehydration.
In Michigan, 44 people had been hospitalized as of July 9.
Heat makes dehydration risk more urgent
Doctors say the current heatwave is making it even more important for people with symptoms to monitor their hydration.
Dr. Larisa Traill, medical director for McLaren Greater Lansing hospital and the McLaren Grand Ledge emergency departments, says her teams are seeing a significant increase in patients coming in with diarrhea symptoms.
“We’re seeing quite a large intake in cases,” Traill said. “The hallmark symptom for cyclosporiasis is frequent, watery diarrhea. It can sometimes be somewhat sudden in onset.”
Patients are also reporting stomach cramps, bloating, gas, nausea, fatigue, loss of appetite and, in some cases, weight loss and low-grade fevers.
Traill said dehydration can become especially dangerous during periods of extreme heat.
“It’s important that pregnant people, the elderly, the very young, those people who are immune compromised or in chemotherapy — we recommend they come in to be seen with signs of dehydration,” she said.
Warning signs include a dry mouth, severe weakness, confusion and feeling light-headed when standing.
Health officials search for the source
More than 1,000 people have been interviewed by local, county and state health officials as investigators work to determine what foods may be linked to the outbreak.
Investigators are asking people what they ate, where they ate it and how their food was prepared.
So far, the strongest clues point toward lettuce or other salad greens as a possible source, though no specific farm or brand has been identified. Health officials say no vegetable has been ruled out.
Ingham County Health Department Medical Director Dr. Nike Shoyinka said the county had more than 300 confirmed cases as of Wednesday, and health officials are continuing efforts to interview affected residents.
Public health teams across Michigan remain in close contact, sharing information about cases and patterns they’re seeing in their communities.
As temperatures climb, health officials say anyone experiencing persistent diarrhea should take extra precautions to avoid dehydration — especially people at higher risk for complications.