CDC alerts clinicians to rising cyclosporiasis cases

Clinical takeaway: Consider Cyclospora infection in patients with prolonged or relapsing watery diarrhea during the May–August cyclosporiasis season—even without international travel—and specifically request Cyclospora stool testing, as routine ova and parasite (O&P) exams may miss the diagnosis.

CDC has issued a Health Alert Network advisory after receiving reports of 1,645 laboratory-confirmed domestically acquired cyclosporiasis cases across 34 states since May 1, 2026, with more than 5,100 additional cases under investigation. This represents a substantial increase compared with 249 cases reported during the same period in 2025. Among confirmed cases with available data, 9% required hospitalization, although no deaths have been reported. CDC, FDA, and state health departments are investigating multiple multistate outbreaks, including one involving more than 400 epidemiologically linked cases, with contaminated fresh produce suspected as a common source.

Symptoms typically develop 2–14 days after exposure (usually about 1 week) and include frequent watery diarrhea, anorexia, weight loss, bloating, nausea, and fatigue. Without treatment, illness may relapse and persist for weeks. Clinicians should obtain recent food and travel histories in suspected cases to support outbreak investigations.

Because routine O&P examinations may not reliably detect Cyclospora, clinicians should specifically request Cyclospora testing or use PCR-based stool assays, when available. Confirmed infections should be treated with trimethoprim-sulfamethoxazole (TMP-SMX) for 7–10 days in immunocompetent adults and children older than 2 months, with longer treatment considered for immunocompromised patients. Supportive care, including maintaining hydration, is also recommended.

Person-to-person transmission is unlikely. In healthcare settings, Standard Precautions remain appropriate, with Contact Precautions for incontinent or diapered patients with gastroenteritis. Laboratories should promptly report confirmed cases to clinicians and public health authorities, and clinicians should report cases according to local requirements to support ongoing surveillance and traceback investigations.

Source: Centers for Disease Control and Prevention. (2026 July 14) CDC Health Alert Network. Domestically Acquired Cyclosporiasis Cases in Multiple U.S. States, 2026 (HAN No. 00531)