The U.S. Centers for Disease Control and Prevention (CDC) has confirmed 1,645 cases of cyclosporiasis, an intestinal infection caused by the cyclospora parasite, as of July 14. Health officials are currently investigating an additional 5,100 suspected cases across 34 states. Michigan remains the hardest-hit state, accounting for 3,309 of the reported cases, according to state and federal data.
Understanding Cyclosporiasis and Transmission
Cyclosporiasis is a gastrointestinal illness contracted by consuming food or water contaminated with feces containing the cyclospora parasite. According to the CDC, the infection is not typically transmitted directly from person to person. Instead, it is most commonly linked to the consumption of raw produce.
While the infection is rarely life-threatening, it can be severe for children, older adults, and individuals with weakened immune systems. If left untreated, the infection may persist for weeks, potentially requiring hospitalization due to dehydration. The CDC recommends a course of the antibiotic trimethoprim-sulfamethoxazole (commonly sold as Bactrim) to treat the infection, with longer treatment durations sometimes necessary for immunocompromised patients, such as those living with HIV.
Did you know?
Past outbreaks of cyclosporiasis have been linked to a variety of fresh produce, including bagged salad mixes, fresh cilantro, basil, raspberries, snow peas, and green onions.
Current Outbreak Status and Surveillance
The current surge in cases began appearing in Michigan, Ohio, West Virginia, and Kentucky on or after June 22. Beyond these initial clusters, states including New York, Illinois, New Jersey, North Carolina, and Texas have each reported 31 or more cases as of July 13. Officials expect these numbers to rise, as reporting delays can cause a lag of up to six weeks between initial exposure and case confirmation.
Gwen Biggerstaff, deputy director of the CDC’s Division of Foodborne, Waterborne and Environmental Diseases, noted that cyclospora is a nationally notifiable pathogen. Healthcare providers in 47 states are legally required to report findings to local public health departments. This data feeds into national surveillance systems, despite recent funding-related changes to the Foodborne Diseases Active Surveillance Network (FoodNet), which ceased tracking six of eight pathogens in July 2025.
FDA Traceback Investigations
The U.S. Food and Drug Administration (FDA) is currently conducting traceback investigations to identify the specific source of contamination. While Michigan health officials have pointed to lettuce as a potential vector, the FDA has not yet linked the outbreak to a specific grower, supplier, or produce type.
Traceback investigations involve gathering detailed dietary histories from infected individuals to map their consumption against the supply chain. This process often requires tracing produce back to the farm of origin. Because cyclospora cases typically increase between May 1 and August 31, public health agencies remain on high alert during these peak months.
Pro Tip: How to Protect Yourself
To minimize the risk of infection, the CDC advises washing hands thoroughly with soap and water before and after preparing raw fruits and vegetables. Always wash produce under running water and use a clean brush to scrub firm items like melons or cucumbers.
Frequently Asked Questions
Can I catch cyclosporiasis from another person?
No. According to the CDC, the parasite is not commonly transmitted directly from person to person. It is primarily spread through the consumption of contaminated water or food.
How long does the infection last if untreated?
Untreated infections can last for several weeks.
Why are case counts for this outbreak still rising?
There is often a significant window between the time a person is exposed to the parasite and the time their illness is confirmed by health authorities.
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