Published August 5, 2026 at 1:33 PM CDT

Missouri health officials confirmed Wednesday that the state is now included in a nationwide outbreak of cyclosporiasis linked to lettuce grown in central Mexico, even though the Centers for Disease Control and Prevention has not yet publicly announced the change.

"We have expected to be added to the multistate outbreak map for a couple weeks now," Missouri Department of Health and Senior Services spokeswoman Lisa Cox said in an email. "It does not change how public health officials investigate the cases reported in Missouri."

Cyclosporiasis, the diarrhea-causing illness caused by a microscopic parasite, has sickened more than 1,000 people in Missouri this summer, far more than usual.

The Washington Post, citing anonymous sources, first reported Tuesday that Missouri was among six additional states added to the outbreak. Publicly, the CDC has only acknowledged that nine states are affected, including Illinois.

Infection is caused when a person eats food – usually produce – contaminated with human waste that carries the microscopic parasite. For example, produce can be contaminated when a sewage pipe breaks and floods a field of lettuce.

Tracking the infection can be difficult. Health workers at local health departments interview people who have tested positive for the parasite about what they ate, and when. They then report that data to state and federal health officials, who incorporate it into the nationwide investigation.

Days or weeks can pass between when a person eats contaminated food and when symptoms, which include diarrhea, cramps, and other digestive issues, show up. By that time, health investigators may have a harder time pinpointing which food is associated with the illness.

The federal Food and Drug Administration has traced sicknesses in states involved in the outbreak to iceberg lettuce, with many people eating at Taco Bell.

Taylor Farms last month issued a voluntary recall of the lettuce, and Taco Bell locations pulled the offending produce. The produce company provided lettuce to food service companies, restaurants in both Illinois and Missouri and retail stories in Missouri.

Although the CDC has – so far – listed nine states as part of the official outbreak, cyclospora infections have been reported in almost all states, according to the agency's latest surveillance data. Because of a lag in reporting, the number of cases listed on federal sites can be lower than those reported by state and local agencies.

Health officials also point out that not every cyclosporiasis cluster may be linked to one cause.

"We're also starting to see that nationwide, not all cases might be tied to this one big outbreak," St. Louis County health department epidemiologist Amanda Brzozowski said during a press conference last week. "We may have other smaller outbreaks in different places."

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