By William Zhu, MD

Centered in the midwestern U.S. and in 30+ states across the country, over 3,000 people have experienced unusually persistent bouts of diarrhea from the parasite cyclospora, according to data collected from the CDC and various state health departments as of July 13th 2026. 

Cyclospora cayetanesis is a coccidian protozoa whose hosts are humans. Transmission occurs when contaminated food or water is consumed usually in the form of raw produce.  Incubation period is around 1-2 weeks making source identification difficult. When a outbreak is detected, there are more infected than reported.

Symptoms are watery, sometimes explosive diarrhea, fatigue and myalgias. These symptoms may persist for weeks with a waxing-waning course. 

Diagnosis requires stool PCR as stool ova parasite tests yield a high false negative rate due intermittent fecal shedding. If in doubt consult infectious disease. Keep other causes of diarrhea like C. Diff, Campylobacter Jejuni and E. Coli on the differential.

Treatment is supportive with correction of fluid loss and electrolyte derangements.  Isolation not required as freshly excreted oocytes and not infectious for over a week. In healthy individuals the infection is typically self limiting.

Preferred antimicrobial agent is trimethoprim-sulfamethoxazole at 160mg TMP+800mg SMX BID for 7-10 days with most individuals experiencing symptom improvement and resolution around 2 days on therapy. Consider prolonged therapy for individuals with immunocompromise. For patients with sulfa allergies ciprofloxacin 500mg BID for 7 days then 3 times a week for 2 weeks is acceptable.

Prevention is centered on washing fresh produce, but cooking all fruits and veggies is the only definitive way to avoid infection as the parasite is resistant to municipal chlorination and conventional washing. Washing produce with soap is not recommended.

References

Sutfin, L. MDHHS updates recommendations for cyclosporiasis prevention. Michigan.gov. https://www.michigan.gov/mdhhs/inside-mdhhs/newsroom/2026/07/13/cyclo-3 (accessed 2026-07-14).

CDC. Surveillance of Cyclosporiasis. Cyclosporiasis. https://www.cdc.gov/cyclosporiasis/php/surveillance/index.html (accessed 2026-07-14).

Hadjilouka A, Tsaltas D. Cyclospora Cayetanensis-Major Outbreaks from Ready to Eat Fresh Fruits and Vegetables. Foods. 2020;9(11):1703. Published 2020 Nov 20. doi:10.3390/foods9111703

Giangaspero A, Gasser RB. Human cyclosporiasis. Lancet Infect Dis. 2019;19(7):e226-e236. doi:10.1016/S1473-3099(18)30789-8

Li J, Cui Z, Qi M, Zhang L. Advances in Cyclosporiasis Diagnosis and Therapeutic Intervention. Front Cell Infect Microbiol. 2020;10:43. Published 2020 Feb 11. doi:10.3389/fcimb.2020.00043