The Food and Drug Administration announced Wednesday that it is probing a new cluster of cyclosporiasis cases involving 72 people. Investigators have not yet determined the source of the contaminated food or water that made them sick, with a formal investigation now underway.
The Centers for Disease Control and Prevention has confirmed 4,173 laboratory-verified, domestically acquired cases since May 1. More than 7,400 additional reports are still under laboratory review, many from Michigan and Ohio. Michigan alone has recorded 7,171 cases this year. Ohio has also seen a considerable increase in cases.
Public health officials portray the broader Midwest situation as one of the largest foodborne outbreaks in the United States in recent years.
Cyclosporiasis is caused by a microscopic parasite that reaches people via contaminated food or water. It produces watery diarrhea, stomach cramps, nausea, and deep fatigue that can persist for days or weeks. No deaths have been reported in either of the outbreaks.
On July 17, U.S. lettuce supplier Taylor Farms recalled iceberg lettuce from central Mexico that had been sold in grocery stores, served in restaurants, and shipped to food-service operators. Mexico responded on Tuesday, stating that there is no evidence yet that lettuce grown in Mexico led to the American cases. The CDC maintains that evidence points to the contaminated produce coming from Mexico.
Taco Bell stopped using Taylor Farms lettuce after some of its restaurants were linked to the outbreak, with shares of Yum Brands, Taco Bell’s parent company, dropping nearly 10 percent last week.
“We believe public health is a shared responsibility among restaurants, their suppliers, and authorities, and we are proud to have consistently acted quickly and proactively to protect our guests,” the company said in a statement. “Taco Bell has taken precautionary action, and we encourage all relevant restaurants, retailers, and foodservice operators to do the same.”
Cyclospora infections emerge every year as temperatures warm, when the parasite thrives. This year’s numbers, however, far exceed the usual seasonal pattern and have forced state and federal teams into extended multi-state investigations.
Their illnesses have not been confirmed as caused by Mexican lettuce or any other specific product. Investigators are reviewing purchase records, restaurant receipts, and patient interviews in a bid to uncover the source. The CDC advises anyone with prolonged diarrhea, cramps, or unexplained fatigue to see a physician and mention the possibility of cyclospora.
The parasite moves only through food or water that has been contaminated somewhere in the supply chain. Cyclosporiasis cases have been reported in 41 states.
Reuters contributed to this report.