Yum shares fall after report US health authorities investigating Taco Bell in cyclosporiasis outbreak

Yum Brands' shares fell as much as 4.5% on Tuesday after the Washington Post reported federal and state health officials were investigating whether lettuce served at Taco Bell may have been associated with an outbreak of cyclosporiasis, an intestinal illness.

The chain has reportedly stopped serving some fresh ingredients - including lettuce - at certain restaurants as a precaution, said the report, citing a person familiar with the matter.

Yum Brands did not immediately respond to a Reuters request for comment.

Cases of cyclosporiasis, which causes diarrhea, nausea and other gastrointestinal symptoms, have risen steadily in recent months across the country. Thirty-four states have reported infections, according to the U.S. Centers ​for Disease Control and Prevention.

The investigation, which is ongoing, is examining whether Taco Bell played a role in one of the largest outbreaks of an illness caused by a foodborne parasite in recent years in the U.S., the report said.

Foodborne illness outbreaks can weigh heavily on restaurant stocks. McDonald's came under scrutiny during a cyclospora outbreak linked to salads in 2018, while Chipotle Mexican Grill faced a series of severe E. coli and norovirus outbreaks across multiple U.S. states, which battered the company's sales and stock price.

"Perception matters as much as the facts in the early stages of a food safety investigation. Even an unconfirmed link to a foodborne illness can cause consumers to rethink where they eat," said Zak Stambor, analyst at eMarketer.

"Even if the chain is ultimately cleared, the investigation could cast a shadow over the brand and weigh on sales in the near term," he added.

Lab-confirmed cases linked to the recent outbreak of cyclosporiasis have risen to 1,645, the CDC said on Tuesday, up by more than 800 cases from its last update a week ago.

The current U.S. outbreak, which began on May 1, is centered in Michigan, while Ohio and New York have also reported high numbers of cases.

Infections across the country have resulted in 141 hospitalizations as of July 13, according to the health agency. No deaths have been reported.

The CDC said it is also aware of more than 5,100 additional cases that require further analysis and confirmation.

Cyclosporiasis can be contracted by consuming food - typically raw fruits and vegetables - or water contaminated with feces, according to the CDC.

(Reporting by Anuja Bharat Mistry, additional reporting by Sanskriti Shekhar in Bengaluru; Editing by Jonathan Ananda)

Copyright Reuters or USA Today Network via Reuters Connect

This story was originally published July 14, 2026 at 2:43 PM.