Michigan's cyclosporiasis outbreak is six times the size of the federal Taco Bell cluster — and its source is still unnamed

There are two cyclosporiasis investigations running in the United States right now, and they are not saying the same thing. Coverage that treats them as one story produces a conclusion neither investigation has reached.

The federal investigation is the one that has named a company. The Centers for Disease Control and Prevention and the Food and Drug Administration have been examining a cluster of 1,947 people across nine states — Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania and West Virginia — who reported eating at Taco Bell. Traceback and interview data pointed to shredded iceberg lettuce grown in central Mexico and supplied by Taylor Farms de Mexico. Around 90 per cent of those interviewed reported eating iceberg lettuce. At least 98 people were hospitalised. Illness onsets run from 22 June to 20 July 2026. On 17 July, Taylor Farms de Mexico voluntarily withdrew all central-Mexico iceberg lettuce from the US market.

The state investigation is much larger and has named nobody. The Michigan Department of Health and Human Services reported 11,234 cases as of 3 August, up from 10,773 on 31 July. That is roughly six times the entire nine-state federal cluster, in one state. It is the largest cyclosporiasis outbreak Michigan has recorded; the state normally identifies around 50 cases in a year. As of 31 July the outbreak had reached 70 of Michigan's 82 counties, and 193 people had been hospitalised as of 30 July.

On the question everyone is searching for — what caused it — MDHHS has not answered. The department says it is still working to identify the direct source and that lettuce or salad greens could be a possible source. Those are two different statements from the ones circulating online, which describe the source as confirmed.

There is a further detail that matters for how firmly the federal link is established. On 18 July the FDA reported that a border surveillance sample of Taylor Farms de Mexico lettuce had tested positive for Cyclospora. On 19 July it withdrew that result, saying laboratory experts had re-reviewed the sample and concluded the finding did not represent true amplification — a false positive. As of that date, no product sample had tested positive for Cyclospora.

The federal case therefore rests on epidemiology and traceback: where sick people ate, what they ate, and where that product came from. That is a legitimate and routine basis for a public-health action, and it is why the voluntary withdrawal stood after the test was retracted. It is not the same as a laboratory result identifying the parasite in the product, and no such result exists.

What connects the two investigations is thin but real. CDC has said it is aware of two cyclosporiasis-related deaths in Michigan among people with underlying health conditions, and counts them as part of the outbreak. MDHHS words it more cautiously: two people with significant underlying health conditions have died and may have been impacted by cyclosporiasis and dehydration. The department also notes that cyclosporiasis is generally not life-threatening and that death from it is uncommon in the United States.

The two counts are not measuring the same thing, and the comparison should be read with that in mind. The federal figure counts only people who reported eating at Taco Bell; Michigan's counts every cyclosporiasis case reported in the state. Michigan is one of the nine states, so some of its cases sit inside the federal cluster as well — neither agency has said how many. What is not explained by either is why one state's total so far exceeds a nine-state cluster tied to a single restaurant chain. Until MDHHS names a source, the honest answer to what is making 11,234 people in Michigan sick is that it has not been established.