California health authorities have identified provisional cases of cyclosporiasis as a fast-growing national outbreak spreads across the United States, though officials say the state’s official case count likely underrepresents the true number of infections.
What this means for residents
The California Department of Public Health has listed 41 provisional cases of cyclosporiasis in 2026. State data also indicate that between 1 and 10 California cases are linked to the broader multistate outbreak investigators are following.
Health officials warn many infections are never confirmed because:
- some people recover without seeking medical care;
- specialized laboratory testing is required to detect the parasite; and
- confirmed cases can take roughly six weeks to be reported to public-health databases.
National picture and local ties
At the national level, federal officials report at least 2,944 illnesses across 32 states. Michigan has reported the largest share, with 1,562 cases — about 31 times its typical annual total — and at least 44 hospitalizations.
In California, most infections identified so far have been associated with international travel rather than with the expanding multistate cluster, the state agency said. Investigators are examining whether contaminated food is driving the broader spike, but they have not pinpointed a specific produce item, supplier or grower as the source.
“with frequent and sometimes explosive bowel movements.”
The Centers for Disease Control and Prevention says the parasite Cyclospora — which causes the illness cyclosporiasis — is typically spread through food or water contaminated with feces. Symptoms can include:
- watery diarrhea;
- nausea and vomiting;
- abdominal pain, bloating and fatigue;
- loss of appetite and weight loss.
Testing, reporting and prevention
Because detecting Cyclospora requires laboratory techniques not used in routine stool testing, clinicians must specifically request testing for the parasite. That, together with delays in laboratory confirmation and reporting, contributes to undercounts in official surveillance figures.
| Data point | Reported figure |
|---|---|
| U.S. illnesses | 2,944 (32 states) |
| Michigan cases | 1,562 |
| U.S. hospitalizations | at least 44 |
| California provisional cases (2026) | 41 |
Public-health officials recommend that residents who develop prolonged diarrhea, severe gastrointestinal symptoms or signs of dehydration seek medical evaluation and tell their clinician about recent travel or any suspect food exposures. Clinicians who suspect Cyclospora should order the appropriate laboratory tests.
Investigations into the outbreak’s cause are ongoing at state and federal levels. Until a specific food item or supplier is identified, officials urge standard food-safety measures: wash produce thoroughly, follow safe food-handling practices, and stay home when sick to avoid spreading infection.
State and federal agencies continue to update case counts and guidance as more lab confirmations are reported.
