US probes 'explosive diarrhea' outbreak linked to Taco Bell lettuce

US health authorities are investigating an outbreak of cyclosporiasis, a parasitic illness colloquially known as "explosive diarrhea" disease. The Centers for Disease Control and Prevention (CDC) has identified a link between hundreds of infections and shredded iceberg lettuce served at Taco Bell restaurants.

The investigation shows the outbreak began weeks before it gained public attention in July. The CDC established May 1 as the start of the 2026 cyclosporiasis season surveillance. Most patients developed symptoms between May 1 and July 9, with a median onset of June 22, indicating the outbreak was spreading before public identification.

By early July, the CDC reported 145 confirmed cases across 17 states. By July 13, the number rose to 1,645 confirmed cases since the season began, with over 5,100 additional cases under analysis. The CDC warned that figures would continue to climb due to delays in diagnosis and reporting.

On July 16, the CDC announced a multi-state outbreak linked to shredded iceberg lettuce at Taco Bell locations in five states. At that time, 1,644 people were ill, with 94 hospitalizations and no reported deaths. Authorities are still working to determine the source of contamination. In total, US health agencies are investigating nearly 7,000 confirmed or suspected cases related to Cyclospora.