The Fourth of July is over. What happens next is arithmetic.

More than 400 Americans across 18 states have been diagnosed with cyclosporiasis since May, and the CDC is investigating [1]. In Michigan alone — where the outbreak clusters in Monroe, Wayne, and Washtenaw counties — the confirmed count reached 680 cases by Sunday, against the state's typical annual total of roughly 50 [2]. Those are the people who already know they are sick.

The parasite does not announce itself quickly. Cyclospora cayetanensis travels on contaminated produce — berries, cilantro, basil, scallions — and takes one to three weeks to produce symptoms [1]. The bowl of fruit salad at the cookout, the pico de gallo, the mesclun mix from the deli counter: all of it is already in the past. The cramping and the exhaustion are still coming.

When symptoms arrive — watery diarrhea, abdominal cramping, nausea, a fatigue that feels disproportionate [2] — the link to a holiday meal will not be obvious [3]. Tell your doctor what you ate and where you traveled. The infection responds to antiparasitic medication when treated.

The CDC, which has cut more than 3,000 positions since early 2025, is investigating without having identified a common food source [1]. Twenty people have been hospitalized nationally; in Michigan, thirty-eight [2].

-- MAYA CALLOWAY, New York