Cyclosporiasis
August 17, 2026
Authors: Claire Alexander, Kamea Lessoway, Ifrah Ahmad, Benjamin Onyango
What is cyclosporiasis?
Cyclosporiasis is a gastrointestinal illness that has recently come into the spotlight due to a sudden increase of cases in the U.S. and South America. This article provides a brief overview of the illness, major actors in the outbreak, and recent updates in the management of this outbreak.
The infection is associated with the protozoan Cyclospora cayetanensis and characterized by explosive watery diarrhea that can last for over a month, loss of appetite, bloating, nausea, and fatigue (Health Alert Network, 2026).
The cycle of reproduction starts from consumption of food or water that is contaminated with human sewage. Symptoms start a week or more after consumption. The oocytes that are shed in sewage mature over a period of two weeks before they are infectious through consumption. Cyclosporiasis is widely endemic in tropical areas where sewage management is not adequate to prevent the cycle of reproduction. The presence of cyclosporiasis in other areas is generally attributed to contaminated food that is imported from endemic areas particularly leafy green vegetables, berries, and herbs. Other mechanisms, such as the natural cycles, are suppressed by cold weather and yet may be possible but have not been documented.
Current Cyclospora Outbreak
The current outbreak in the US began at the beginning of May with rapidly increasing cases in a few states and expanded more widely. The outbreak has a high concentration of cases in southeast Michigan near Lake Erie and the adjacent areas of Ohio, but is also present in significantly lower reported numbers in many other states around the country. As of August 05, Michigan has exceeded 12,000 cases, much higher than 50 cases in prior years and other states around the country this year (Michigan Department of Health and Human Services, 2026; Wethington, 2026).
Across the United States, over 20,000 people (Thanawala, 2026) have developed cyclosporiasis this year and hundreds of people have been hospitalized (United States Centers for Disease Control and Prevention, 2026a). On August 3, 2026, it was announced that two people have died of Cyclospora in Michigan (Michigan Department of Health and Human Services, 2026; Thanawala, 2026).
Government Response and Reduced Surveillance
Currently, the U.S. Centers for Disease Control and Prevention (CDC) Foodborne Diseases Active Surveillance Network (FoodNet) surveillance for two pathogens: Salmonella, and Shiga toxin-producing E. coli (STEC) (United States Centers for Disease Control and Prevention, 2026b). Historically, FoodNet surveilled for 9 pathogens: Campylobacter, Cyclospora, Listeria, Salmonella, Shiga toxin-producing E. coli (STEC), Shigella, Vibrio, Yersinia, and Cryptosporidium. Cryptosporidium surveillance was cut in 2017, and six of the remaining eight, including Cyclospora, were made optional on July 1, 2025 (United States Centers for Disease Control and Prevention, 2026b).
FoodNet is a joint collaboration between the CDC, USDA-FSIS, FDA, and 10 state health departments, where personnel share information about infections and case information with the CDC (United States Centers for Disease Control and Prevention, 2026b). 47 States have mandatory state reporting for Cyclosporiasis, and cases are voluntarily reported by states to the CDC via the National Notifiable Diseases Surveillance System (NNDSS) (United States Centers for Disease Control and Prevention, 2026c; Glenza, 2026).
This is also a concern as not all states have the same capacity to monitor without a federal surveillance system. While states such as Maryland, California, Minnesota, and New York are reported to have more robust food monitoring systems, places such as Alabama and South Carolina have far less capacity (Winny, 2026).
FoodNet was not designed to detect outbreaks (United States Centers for Disease Control and Prevention, 2026b), but recent cuts to federal food safety systems in general and the reporting requirement for cyclosporiasis in particular leave the country more vulnerable to food-borne illnesses (Winny, 2026).
Lettuce Recalls and Taylor Farms
It has recently been reported that iceberg lettuce distributed by Taylor Farms has been linked to the outbreak in 15 different states (United States Food and Drug Administration, 2026). Since Taylor Farms’ iceberg lettuce was sold in at least 31 states, the number of states with documented cases is likely to increase. Taylor Farms issued a recall on July 17, 2026, for certain Marketside brand lettuce products with ‘Best if Used By’ dates between July 18 and August 3, 2026 (United States Centers for Disease Control and Prevention, 2026a).
Prevention and Treatment
Preventing cyclosporiasis avoids weeks of explosive diarrhea, fatigue, and dehydration. Avoid foods that are likely to be contaminated, such as shredded lettuce and cilantro (United States Centers for Disease Control and Prevention, 2026a). Avoid raw produce with crevices that are hard to wash, such as raspberries, blackberries, leafy greens, and fresh herbs. If possible, remove and discard the outer leaves of produce, such as a head of lettuce. Wash produce, even if it is marked as “prewashed,” and wash your hands before and after preparing food (Linder & Malani, 2026).
Cooking food, including vegetables, is an effective way to prevent cyclosporiasis (Linder & Malani, 2026). Heating to 70°C (161°F) for 15 minutes can inactivate Cyclospora oocysts (Sathyanarayanan & Ortega, 2006). Home freezers do not reach the low temperatures required to kill Cyclospora oocysts (Sathyanarayanan & Ortega, 2006), so freezing or refrigerating food does not eliminate risk (Moore, 2026).
Cases of cyclosporiasis are diagnosed through visual microscopic analysis or PCR (polymerase chain reaction) testing of stool samples (Linder & Malani, 2026). Microscopic analysis is less sensitive and can have false positives or false negative results (Li et al., 2019).
Cyclosporiasis is typically treated with a seven-to-ten day course of trimethoprim-sulfamethoxazole (Linder & Malani, 2026). Patients who cannot take sulfa drugs may be treated with ciprofloxacin or nitazoxanide (Li et al., 2019). Supportive care with fluids is also important to prevent dehydration (Linder & Malani, 2026).
References
Glenza, J. (2026, July 28). Cyclosporiasis cases show ‘vulnerabilities’ in US food safety system, experts say. The Guardian. Retrieved August 6, 2026, from https://www.theguardian.com/us-news/2026/jul/28/cyclosporiasis-outbreak-us-food-safety
Health Alert Network. (2026, July 14). Domestically acquired cyclosporiasis cases in multiple U.S. states, 2026. United States Centers for Disease Control and Prevention. https://www.cdc.gov/han/php/notices/han00531.html
Li, J., Wang, R., Chen, Y., Xiao, L., & Zhang, L. (2019). Cyclospora cayetanensis infection in humans: Biological characteristics, clinical features, epidemiology, detection method and treatment. Parasitology, 147(2), 160-170. https://doi.org/10.1017/S0031182019001471
Linder, K. A., & Malani, P. N. (2026, July 21). What is cyclosporiasis? JAMA. Advance online publication. https://doi.org/10.1001/jama.2026.14866
Michigan Department of Health and Human Services. (2026). Infectious disease outbreaks. State of Michigan. Retrieved August 16, 2026, from https://www.michigan.gov/mdhhs/keep-mi-healthy/infectious-diseases/infectious-disease-outbreaks
Moore, J. (2026, July 21). Cyclospora outbreak: Answers to your most common questions. North Carolina State University: CALS News. https://cals.ncsu.edu/news/cyclospora-outbreak-answers-to-your-most-common-questions/
Sathyanarayanan, L., & Ortega, Y. (2006). Effects of temperature and different food matrices on Cyclospora cayetanensis oocyst sporulation. Journal of Parasitology, 92(2), 218-222. https://doi.org/10.1645/GE-630R.1
Thanawala, S. (2026, August 3). Michigan reports first 2 U.S. deaths in outbreak of cyclospora. CBS. https://www.pbs.org/newshour/health/michigan-reports-first-2-u-s-deaths-in-outbreak-of-cyclospora
United States Centers for Disease Control and Prevention. (2026a, August 13). Cyclospora outbreak linked to iceberg lettuce. United States Department of Health and Human Services. Retrieved August 16, 2026, from https://www.cdc.gov/cyclosporiasis/outbreaks/07-26/index.html
United States Centers for Disease Control and Prevention. (2026b, April 28). Foodborne Diseases Active Surveillance Network. About FoodNet. https://www.cdc.gov/foodnet/about/index.html
United States Centers for Disease Control and Prevention. (2026c, January 8). Surveillance of cyclosporiasis. United States Department of Health and Human Services. Retrieved August 16, 2026, from https://www.cdc.gov/cyclosporiasis/php/surveillance/index.html
United States Food and Drug Administration. (2026, August 5). Investigation of 15-state outbreak of cyclospora illnesses: Iceberg lettuce (July 2026). United States Department of Health and Human Services. Retrieved August 5, 2026, from https://www.fda.gov/food/outbreaks-foodborne-illness/investigation-15-state-outbreak-cyclospora-illnesses-iceberg-lettuce-july-2026
Wethington, P. (2026, August 5). Michigan cyclosporiasis case count jumps by 715 cases, total now over 12,000. CBS. https://www.cbsnews.com/detroit/news/michigan-cyclosporiasis-over-12000-cases/
Winny, A. (2026, July 22). Understanding the Cyclosporiasis Outbreak | Johns Hopkins | Bloomberg School of Public Health. Johns Hopkins Bloomberg School of Public Health. Retrieved August 6, 2026, from https://publichealth.jhu.edu/2026/understanding-the-cyclosporiasis-outbreak