Taco Bell's ties to "explosive" diarrhea outbreak threatens Yum Brands' crown jewel

• "I think Taco Bell is going to take a big hit in the public eye," University of Michigan business professor Erik Gordon tells Axios. "This is the kind of thing that goes viral."

The big picture: The FDA and CDC confirmed Thursday that they are investigating an outbreak of cyclosporiasis at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia.

• The intestinal illness can cause "explosive" or "watery" diarrhea.
• The agencies linked the outbreak to shredded iceberg lettuce sold at Taco Bell and warned consumers not to eat it at locations in the affected states.
• Agencies have already identified more than 1,600 cases, including 94 hospitalizations. Michigan officials said they've identified more than 5,000 cases of cyclosporiasis, without identifying Taco Bell.

Taco Bell said it "has taken immediate action to voluntarily remove potentially impacted lettuce from a supplier in select states," adding that it's been "indefinitely removed from our supply chain nationwide and will be replaced within 24 hours in select states."

Flashback: Past crises have dealt bruising blows to restaurant chains.

• Chipotle's same-store sales plunged 14.6% in the fourth quarter of 2015 with an outbreak of norovirus and E. coli. The downturn ultimately lasted about two years, according to TD Cowen food industry analyst Andrew Charles, as the chain was forced to overhaul its food safety procedures.
• Taco Bell sales declined 5% in the fourth quarter of 2006 during an E. coli crisis that ultimately dampened sales for four quarters, according to Charles.
• McDonald's sales fell 1.4% in the fourth quarter of 2024 during an E.coli crisis linked to its slivered onions in an episode that the company quickly contained.

What they're saying: Social media chatter about the Taco Bell crisis has spread far beyond the affected states.

• Charles pointed out that social media "has shortened consumers' attention spans," potentially limiting the long-term damage for the brand.
• But Gordon says this case is different: "We do have short attention spans and jump to the news of the minute, but because this involves diarrhea, there will be memes that last. Stories have a short lifetime; memes have a long lifetime."

Threat level: The crisis threatens to thwart momentum for Taco Bell, which has been the one dependable chain for Yum Brands.

• Taco Bell's same-store sales were up 8% in the first quarter of 2026, compared with only 2% for the company's KFC chain and flat sales for Pizza Hut, which it recently agreed to sell.

• "This is the only Yum brand that doesn't look old and tired," Gordon says. "It's the engine of their sales, it's the engine of their profits, and it's gone off the tracks."

The latest: There are early signs that foot traffic is already waning. Visits to Taco Bell restaurants nationwide on July 9, 10 and 11 were 0.9%, 4.6% and 5.8% below the average for comparable days during the first half of the year, according to Placer.ai.

• Yum shares fell 9% from July 7-16, and were trading down another 2% Friday afternoon.

What we're watching: Like others before it, Yum could face pressure to overhaul its food safety procedures or even cut off its supplier.

• Taylor Farms supplied the lettuce to Taco Bell, according to officials who spoke to AP, CBS News and WSJ.
• It was the same supplier involved in the 2024 E. coli outbreak linked to McDonald's. Yum Brands had removed fresh onions from select Taco Bell, KFC and Pizza Hut restaurants at the time "out of an abundance of caution."
• Taylor reps did not respond to a request for comment.

"If Taco Bell were applying lessons from past outbreaks, they will likely aim to rebuild consumer trust and review supply chain practices," CFRA Research restaurant analyst Alex Fasciano tells Axios in an email, noting that Yum has "strong supply chain practices, making traceability easier in outbreak cases."