(Bloomberg) — The US Food and Drug Administration said it’s investigating yet another outbreak of the diarrhea-causing cyclospora parasite, with 72 cases tied to an unknown source.
The latest infections disclosed by the agency on Wednesday add to the surge of cases centered in the Midwest. Those were linked to Taylor Farms lettuce, and the company has recalled those products. The FDA already was investigating several other ongoing cyclospora clusters.
The outbreaks are roiling consumers and spooking investors. While the FDA said the latest outbreak hasn’t been linked to an identifiable product, shares of Sweetgreen Inc. fell more than 13% at 3:25 p.m. in New York and Chipotle Mexican Grill Inc. fell more than 4% to a session low. Neither company has been linked to outbreaks to date.
Yum! Brands Inc., whose Taco Bell chain was previously linked to the Taylor Farms cases, fell as much as 1.4%.
Sweetgreen and Yum pared those losses by the close of trading, with Yum closing up slightly for the day.
The parasite is notoriously difficult to trace to a particular product or a source. A person typically develops symptoms up to two weeks after ingesting the parasite, long after receipts have been thrown away and potential clues to the cause of the disease have been forgotten.
The FDA’s addition of a new outbreak leaves much to the imagination — there are no additional details about which states have been affected.
Cyclospora cases rise every summer as the warmer season allows the parasite to thrive. Thousands of people have been infected across 41 states so far this summer, according to the US Centers for Disease Control and Prevention. At least 300 have been hospitalized, the public health agency said Tuesday.
There are typically fewer than 100 cases nationwide for the entire year.
The FDA previously linked a false positive lab test to Taylor Farms lettuce — stopping short of expanding the existing recall. However, the move did not clear the produce company from culpability. The agency’s investigation with the CDC and state health departments found the majority of sick people had eaten at Taco Bell locations in the Midwest that sourced iceberg lettuce from Taylor Farms. The company said it was “voluntarily removing all iceberg lettuce sourced from central Mexico.”
The messaging and delays from Taylor Farms and the FDA sparked confusion among customers about what was safe to consume.
(Updates with additional details throughout.)
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