Michigan health officials said on Thursday that confirmed cases of cyclosporiasis in the state have climbed to 4,312, an increase of 550 cases from the previous day, as investigators continue searching for the source of an outbreak of the intestinal illness that has grown far larger than any seen in recent years.
The outbreak has led to 102 hospitalizations in Michigan as of Thursday, according to the state’s Department of Health and Human Services. No deaths have been linked to the cyclosporiasis outbreak so far, but health officials say the rapid rise in confirmed cases has made this year’s outbreak notably more severe than past cyclosporiasis events in the region.
Cyclosporiasis is a parasitic intestinal infection caused by the microscopic parasite Cyclospora cayetanensis. People typically contract the disease by eating food, most often raw fruits and vegetables, or drinking water that has been contaminated with feces containing the parasite. Symptoms include watery diarrhea, nausea, cramping, fatigue and other gastrointestinal problems that can last for weeks if untreated.
While the United States has recorded cyclosporiasis outbreaks in previous summers, health officials say the scale and geographic reach of this year’s outbreak stand out. The current wave of cyclosporiasis began around May 1 and is centered in Michigan, though Ohio and New York have also reported unusually high numbers of the disease cases in recent weeks, suggesting the contamination source may have been distributed across state lines.
Nationally, the picture is even larger. According to the U.S. Centers for Disease Control and Prevention’s most recent update, laboratories have confirmed 1,645 cyclosporiasis cases across 34 states since May, with 141 people hospitalized as a result of the illness nationwide. The CDC said it was also investigating roughly 5,100 additional possible cyclosporiasis cases that have not yet been laboratory-confirmed, a sign that the true scope of the outbreak could grow substantially in the coming weeks as testing continues.
Michigan health officials have identified lettuce as a potential source of the cyclosporiasis outbreak, but investigators have not yet linked any specific type of produce, grower or supplier to the illnesses. The Food and Drug Administration is now conducting traceback investigations on multiple produce items, including lettuce, in an effort to pinpoint exactly where the contamination originated and to prevent further spread of the parasite through the food supply.
Public health experts note that cyclosporiasis outbreaks can be especially difficult to trace because symptoms often take a week or more to appear after exposure, and because the parasite can survive on produce even after routine washing. That delay between exposure and illness, combined with the wide distribution networks used by grocery stores and restaurants, has historically made it challenging for investigators to identify a single source once a cyclosporiasis outbreak is already underway.
Health officials in Michigan are urging residents who develop prolonged diarrhea or other gastrointestinal symptoms to seek medical attention and mention any recent consumption of raw produce, so that healthcare providers can test for cyclosporiasis specifically, since standard stool tests do not always detect the parasite. Doctors say cyclosporiasis is treatable with antibiotics once diagnosed, and most patients recover fully, though the illness can be prolonged and debilitating without proper treatment.
As the cyclosporiasis case count continues to rise, both state and federal investigators say identifying the contaminated product remains the top priority, with the hope that pinpointing the source will allow officials to issue targeted recalls and prevent the outbreak from expanding further across additional states.
