Five states have now reported 1,644 people infected with Cyclospora who ate at Taco Bell before becoming ill, in an outbreak federal investigators have traced to shredded iceberg lettuce from a single supplier in Mexico. Ninety-four people have been hospitalised. No deaths have been reported.
The cases are in Indiana, Kentucky, Michigan, Ohio and West Virginia, with illness onset dates running from May 13 to July 13. The Food and Drug Administration's traceback investigation converged on Taylor Farms de Mexico as the common supplier of shredded iceberg lettuce to the restaurants where sick people had eaten. On July 17 the company said it was voluntarily removing all iceberg lettuce sourced from central Mexico from the United States market.
Cyclospora cayetanensis is a microscopic parasite spread when food or water contaminated with faeces is swallowed. It does not pass directly from person to person, which is why outbreaks trace back to a product rather than spreading through a community. Symptoms usually begin about a week after exposure and are dominated by watery diarrhoea that can be prolonged and can relapse after apparently clearing; loss of appetite, weight loss, cramping, bloating, nausea and fatigue are common. Untreated, an infection can last from a few days to a month or more. It is treated with antibiotics.
The foods involved are almost always fresh produce eaten raw and hard to wash clean. Past US outbreaks have been tied to imported raspberries, basil, cilantro, snow peas and, repeatedly, leafy greens. The parasite needs days to weeks in the environment after being shed before it becomes infectious, which means contamination generally happens well before the food reaches a kitchen — one reason traceback investigations tend to end at a grower or processor rather than at a restaurant.
The size of this outbreak is what sets it apart. In 2018 the CDC recorded two large multistate cyclosporiasis outbreaks in the same season: 250 laboratory-confirmed cases from prepackaged vegetable trays sold at a Midwest convenience-store chain, and 511 from salads sold at a fast-food chain that pulled the product from roughly 3,000 stores across 14 states. The current five-state figure is more than twice their combined total, though the categories are not identical — the earlier counts were laboratory-confirmed, while this one counts reported cases with a known exposure.
Officials also caution that the reported figure understates the true number. Cyclosporiasis is diagnosed by a specific stool test that is not part of a routine workup, so infections are only counted when a clinician thinks to order it; mild cases that resolve on their own are rarely captured at all. Cases have been identified in 34 states this year, though not all are connected to this outbreak.
The investigation into how the lettuce became contaminated is continuing. Cyclospora is endemic in parts of Central and South America, and US outbreaks have historically clustered in the spring and summer months when imported produce volumes are highest.