Cyclospora Cases Run More Than Six Times Last Year's Level

The CDC has received reports of 1,645 confirmed domestically acquired cases of cyclosporiasis since 1 May 2026, and is aware of more than 5,100 further cases requiring additional analysis to confirm domestic acquisition.

The comparison that defines the outbreak: 249 cases had been reported nationally by the same point last year.

What cyclospora is

Cyclospora is a microscopic parasite transmitted through contaminated food or water. It causes prolonged gastrointestinal illness — watery diarrhoea, cramping, fatigue and weight loss — that can persist for weeks and frequently relapses without treatment.

Two features make it unusually difficult to control:

• It is not transmitted person to person, so every case traces back to a contaminated source.
• The parasite requires days to weeks outside a host before becoming infectious, meaning contamination typically occurs well before consumption — usually in growing or processing.

That second point is what makes outbreaks hard to trace. By the time cases appear, the implicated produce has often been eaten, discarded or moved through the supply chain.

Four investigations at once

The FDA is investigating four separate cyclospora outbreaks in 2026. Multiple simultaneous outbreaks suggest either several independent contamination events or a shared upstream source that traceback has not yet isolated.

Why the case counts understate the problem

Confirming cyclospora requires a specific laboratory test that is not part of routine stool panels everywhere. A patient must seek care, a clinician must suspect the parasite, and the right test must be ordered.

Each of those steps loses cases. The true burden is certainly higher than the confirmed figure, and the gap between 1,645 confirmed and 5,100+ awaiting analysis illustrates the scale of the lag.

What can be done

Cyclospora is not reliably removed by washing produce, and it is not killed by standard sanitising treatments. Cooking is effective; rinsing is not sufficient.

The durable fix sits upstream — water quality and hygiene practices in growing regions — which is a supply chain problem rather than a consumer one, and is the reason the same outbreaks recur seasonally.