CDC investigates multistate cyclosporiasis outbreak with nearly 7,000 suspected cases

The Centers for Disease Control and Prevention reported 1,645 laboratory-confirmed cases of domestically acquired cyclosporiasis across 34 states since May 1, 2026, with nearly 7,000 suspected cases under investigation as of July 14. Officials said the CDC, FDA, and state health departments are working to identify the source of multiple multistate outbreaks but have not yet confirmed a specific food item.

Officials said an additional 5,100 suspected cases are under review to determine whether they are domestically acquired, potentially raising the total number of cases to nearly 7,000. The CDC noted that 141 patients have been hospitalized, and no deaths have been reported in connection with the outbreak.

As of July 13, 2026, the Centers for Disease Control and Prevention reported 1,645 laboratory-confirmed cases of domestically acquired cyclosporiasis across 34 states, with illness onset dating back to May 1.

The agency emphasized that the outbreak is widespread and involves multiple multistate clusters. One notable cluster includes more than 400 cases spanning at least four Midwestern states: Michigan, Ohio, West Virginia, and Kentucky. Officials said these cases appear epidemiologically linked, suggesting a common source of infection, though no specific food or water vehicle has been confirmed. Michigan alone has reported nearly 1,000 cyclosporiasis cases in 2026, marking the largest outbreak in the state’s history and one of the largest in the United States in recent years, according to state health department records.

The CDC, Food and Drug Administration, and state and local health departments are coordinating investigations to identify the sources of infection. On July 14, the CDC issued a health advisory warning clinicians and the public about the increase in domestically acquired cyclosporiasis cases and the emerging multistate outbreak patterns. The advisory urged healthcare providers to consider cyclosporiasis in patients with prolonged or unexplained watery diarrhea and to order appropriate diagnostic testing, including stool examinations for the parasite *Cyclospora cayetanensis*. The CDC has activated its Emergency Operations Center to support the outbreak response, reflecting a coordinated national effort.

The median age of confirmed domestic case-patients is 44 years, with ages ranging from 2 to 95, and 56% of patients are female, according to CDC data. The median illness onset date among confirmed cases is June 22, with onset dates spanning from May 1 to July 9, indicating peak activity in late spring and early summer. In addition to domestically acquired cases, the CDC reported 440 cases classified as travel-associated, where illness developed after international travel within 14 days before onset.

Officials said the investigations have not yet identified a specific food item responsible for the outbreaks. While prior outbreaks in the United States have been linked to fresh produce such as salad mixes and cilantro imported from Mexico, the CDC and FDA stated that no particular product has been confirmed in the current events. Earlier this year, some illness clusters were associated with Mexican-style restaurants, a grocery chain, and a catered event, but these have not been publicly confirmed as sources for the national surge in cases.

Cyclosporiasis is an intestinal illness caused by the parasite *Cyclospora cayetanensis*, which is transmitted through ingestion of food or water contaminated with feces containing the parasite’s oocysts. Common symptoms include watery diarrhea, cramping, bloating, increased gas, nausea, fatigue, and weight loss. The illness can cause prolonged or relapsing diarrhea lasting weeks if untreated, but most otherwise healthy individuals recover with antibiotic treatment, typically trimethoprim-sulfamethoxazole. The parasite is generally not spread directly between people because the oocysts require time in the environment to become infectious. Vulnerable populations such as young children, older adults, and immunocompromised individuals may be at greater risk for dehydration and complications, which may explain the hospitalizations recorded in this outbreak.

Public health officials advise thorough washing of fresh produce under clean running water and adherence to food safety and hand hygiene practices to reduce the risk of infection. During the Michigan cluster, health authorities recommended consumers purchase whole heads of lettuce rather than prewashed, bagged salads, remove the outer two to three leaves, and wash the remaining leaves carefully. The CDC’s advisory also stressed the importance of reporting confirmed cases to state health departments to improve surveillance and outbreak investigations.

The CDC continues to work closely with the FDA and jurisdictional partners to analyze epidemiologic and genotyping data as investigations proceed. Officials noted that case counts are expected to rise as additional illnesses are confirmed and classified. The agency’s surveillance and outbreak pages will be updated with new information as it becomes available.