Understanding Cyclosporiasis: Recent Outbreak Insights

It’s been some time since my last post, but here we are! Today’s topic is Cyclosporiasis, and I am certain that you have come across news articles about the recent outbreak, such as the one titled “Outbreak of diarrhea caused by parasite jumps to more than 3,000 cases.”  Let’s explore why this outbreak is happening and what steps you can take to avoid contracting this illness yourself.

A brief background about Cyclosporiasis

The cause of Cyclosporiasis is not a virus or bacteria. It is a parasite called Cyclospora cayentanensis. This parasite was not known in the United States until 1990, when the first case occurred in Chicago, Illinois (J Bogitsh 2013). While the Cyclospora parasite is not exclusive to the U.S., it has been identified in several regions, including Central and South America, the Caribbean, Central Asia, the Indian subcontinent, and the Middle East (J Bogitsh, 2013; Almeria, S., et al, 2019). Among the various species of Cyclospora, only C. cayentanensis is known to infect humans (Almeria, S., et al, 2019).

CDC. (2024, March 4). Clinical Overview of. Cyclosporiasis. https://www.cdc.gov/cyclosporiasis/hcp/clinical-overview/index.html

The FoodNet network, a system for monitoring food safety, tracked cases of cyclosporiasis from 1997 through July 2025. However, this monitoring has ended, as the requirement for mandatory reporting was removed last year (CDC, 2026). As a result, the CDC does not have an accurate count of how many cases are currently present in the United States, or whether the outbreak is growing. Nor have they pinpointed a source of the contamination. According to ABC News, the number of cases in Michigan alone has exceeded 2,600, according to the Michigan Department of Health and Human Services (ABC, 2026). As you can see from the chart below, the cases are increasing in both number and geographic reach. The CDC’s FoodNet system now only tracks Salmonella and E.coli (both STEC and non-STEC) (CDC, 2026). As you can see in the figure below, the cases are increasing in both number and range.

https://www.cdc.gov/cyclosporiasis/php/surveillance/index.html

How do you know if you have contracted cyclosporiasis?   

Cyclosporiasis is characterized by severe, explosive diarrhea, fever, nausea, and stomach cramps.

Other symptoms include loss of appetite, weight loss, dehydration, gas and/or bloating, body aches, and headaches. However, some people may not experience any symptoms at all (Matthew, 2017). Symptoms typically appear within two days of ingesting the parasite, though they may take up to two weeks to show (CDC, 2026). The condition can be treated with trimethoprim-sulfamethoxazole (CDC, 2026); however, prevention is the best approach. If you suspect you have cyclosporiasis, it is important to see your doctor for proper testing and treatment.

The lifecycle of Cyclospora catetanensis

How can you prevent infection?

People with weakened immune systems, such as the elderly, young children, or those who have traveled to areas where Cyclospora is common, are at a higher risk of infection compared to healthy adults.

In the past, certain foods like raspberries, basil, parsley, snow peas, and leafy greens have been linked to the parasite. However, in the current outbreak, no single source has been identified. The general recommendation is to thoroughly wash any produce before consuming it. The parasite can stick to fruits and vegetables, so a quick rinse may not always remove the parasite or its oocysts. The parasite can also be spread through environmental contamination during the growing process, such as soil, water, and feces, and through irrigation water, and through human handling or contaminated equipment during postharvest processes (Matthews, 2017). Cooking produce thoroughly is more effective at reducing the risk of infection than eating it raw and unwashed. Lastly, frequent handwashing is important to prevent the spread of parasites. Since the parasite spreads through the oral-fecal route, as seen in the preceding figure,  proper hand hygiene is crucial, especially after handling anything that may have come into contact with contaminated environments.

If you have questions, please email me. I will be happy to answer your questions to the best of my ability. Are there food safety topics you would like to see? Reach out in the “contact us” portion of my website!

References

J Bogitsh, B. (2013). HUMAN PARASITOLOGY FOURTH EDITION. Elsevier. 148-149. http://125.212.201.8:6008/handle/DHKTYTHD_123/5867

Almeria, S., Cinar, H. N., & Dubey, J. P. (2019). Cyclospora cayetanensis and cyclosporiasis: An update. Microorganisms, 7(9), E317. https://doi.org/10.3390/microorganisms7090317

CDC. (2024, September 17). About FoodNet. Foodborne Diseases Active Surveillance. Accessed July 13, 2026.  Network. https://www.cdc.gov/foodnet/about/index.html.

Kekatos, M. (2026, July 13). Cyclosporiasis cases in Michigan surpass 2,600, health officials say. ABC News. https://abcnews.com/Health/cyclosporiasis-cases-michigan-surpass-2600-health-officials/story?id=134709100

Matthews, K. R., Kniel, K. E., & Montville, T. J. (2017). Food Microbiology: An Introduction: Vol. 4th Edition (pp. 399–403). John Wiley & Sons. https://play.google.com/store/books/details?id=r1zqDwAAQBAJ CDC. (2026, July 10).

Surveillance of. Cyclosporiasis. https://www.cdc.gov/cyclosporiasis/php/surveillance/index.html