The 2026 cyclospora outbreak, explained

What is cyclospora?

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; 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, so contamination generally happens at a grower or processor, well before the food reaches a kitchen.

How big is the outbreak?

The CDC's outbreak count — laboratory-confirmed cases linked to Taco Bell exposure — stood at 1,947 across nine states as of July 26, 2026, up from 1,644 in five states a week earlier, with at least 98 hospitalisations and no deaths. For scale, the two largest multistate cyclosporiasis outbreaks the CDC documented in 2018 produced 250 and 511 laboratory-confirmed cases — 761 between them. This outbreak is more than double their combined total.

The outbreak figure is also only part of the season. Nationally, the CDC has recorded 4,173 laboratory-confirmed cyclosporiasis cases since May 1 and says it is aware of more than 7,400 further cases not yet confirmed — many reported by Michigan and Ohio. In a normal year, US cyclosporiasis runs at a fraction of this volume, which is why the agency moved to weekly surveillance updates for 2026.

Every one of these counts is a floor. Cyclosporiasis is diagnosed by a specific stool test that is not part of a routine workup, so infections are recorded only when a clinician thinks to order it, and mild cases that clear on their own are rarely captured at all.

Why do Michigan's numbers look so different from the CDC's?

Because they count different things. Michigan's health department has reported over 7,000 cyclosporiasis cases statewide — more than four times the federal outbreak figure at the time — and the gap is a matter of denominators, not disagreement. Michigan publishes a statewide total that includes probable cases; the CDC's outbreak count includes only laboratory-confirmed infections that are also linked to Taco Bell exposure. As the CDC itself puts it: "CDC's surveillance updates do not include probable cases. State data may include probable and confirmed cases, resulting in higher case counts than what CDC reports."

The general rule, which The Fold learned by getting this wrong before correcting it: when a state and a federal count disagree, check whether they are counting the same population before calling it a disagreement. Michigan's outbreak spans 65 of its 82 counties, with the heaviest totals in the south-east — Wayne, Washtenaw, Oakland and Ingham counties.

What is the evidence against the lettuce?

Epidemiology and traceback — not a laboratory match. The FDA'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 18 the agency announced a positive cyclospora test on a lettuce sample; on July 19 it withdrew the finding as a false positive that did "not represent true amplification." As of that withdrawal there were no confirmed positive samples at all.

That is less unusual than it sounds. Foodborne outbreaks are frequently solved without recovering the pathogen from a sample, because suspect product is usually eaten or thrown away long before investigators reach it. And the case pattern points at the food independently: of roughly 4,300 Michigan cases classified by age, just 20 were in children under ten — consistent with a food adults eat routinely and small children largely do not, which is about the profile of salad greens.

Does the recall explain the outbreak?

Not most of it, on the CDC's own numbers. The outbreak's 1,947 cases represent about 47 percent of the 4,173 laboratory-confirmed cases recorded nationally this season — and about 17 percent of the roughly 11,600 cases the agency has either confirmed or is aware of. The remainder are cases the CDC has not tied to Taylor Farms de Mexico.

These shares will move. Cyclospora takes as long as six weeks to confirm as outbreak-associated, so some of the unconfirmed reports will be added to the outbreak total in the coming weeks, raising the recall's share; others will resolve as unrelated, lowering it. But the residual is large enough that a second vehicle, or a wider distribution chain, cannot yet be ruled out.

What has been recalled?

On July 17, Taylor Farms de Mexico voluntarily removed all iceberg lettuce sourced from central Mexico from the US market. The recall has since widened beyond restaurants into retail, covering Marketside-brand product sold at Walmart — moving the exposure from a foodservice problem, where a diner has no way of knowing which supplier fed a given restaurant, to a retail one, where consumers can check a bag in their own refrigerator.