Cyclosporiasis is an intestinal infection caused by the microscopic parasite Cyclospora cayetanensis. People become infected by ingesting food or water contaminated with the parasite's oocysts, which are not infectious immediately after being shed, requiring days to weeks in the environment to sporulate. The disease causes watery diarrhea, cramping, bloating, nausea, and fatigue, with symptoms appearing about one week after exposure. In the United States, cyclosporiasis is not endemic; most cases occur in travelers returning from tropical or subtropical regions, but domestically acquired outbreaks have been linked to imported fresh produce, particularly raspberries, basil, cilantro, and salad mixes. The U.S. Centers for Disease Control and Prevention (CDC) tracks reported cases through the National Notifiable Diseases Surveillance System, and outbreaks are investigated by state and federal public health agencies. Annual case counts in the U.S. have varied widely. Between 2000 and 2010, reported cases averaged roughly 200 to 300 per year. A major spike occurred in 2013 when 631 cases were reported, primarily linked to a salad mix from a Mexican supplier. In 2018, a record 2,299 cases were reported, with multiple outbreaks traced to vegetable trays and cilantro from Mexico. The 2019 season saw 2,408 cases, the highest on record, followed by 1,241 cases in 2020. The COVID-19 pandemic likely disrupted food supply chains and reduced travel, contributing to lower case counts in 2020 and 2021, though 2021 still saw 1,225 cases. The CDC and FDA have implemented import alerts and testing protocols for high-risk produce, but outbreaks continue to occur. The prediction market question asks whether total reported cyclosporiasis cases in the U.S. during 2026 will exceed a specific threshold. The resolution date is January 8, 2027, with cases backdated to 2026 if reported after the calendar year but before the deadline. This market attracts interest from epidemiologists, food safety professionals, and public health officials who monitor seasonal patterns and regulatory changes. Factors influencing case counts include the volume of imported produce from endemic areas, FDA enforcement actions, climate conditions affecting parasite survival, and changes in diagnostic reporting practices. The market also reflects broader concerns about foodborne illness surveillance and the effectiveness of preventive controls under the Food Safety Modernization Act.

Historical Context

Cyclosporiasis was first recognized as a human disease in the 1970s, with the first confirmed U.S. outbreak in 1990 in Chicago, linked to contaminated water. The parasite was officially named Cyclospora cayetanensis in 1993. The first major foodborne outbreak occurred in 1996, when 1,465 cases in the U.S. and Canada were traced to Guatemalan raspberries. That outbreak led to a temporary import ban and the development of the FDA's import alert system for Cyclospora. In 2013, a multistate outbreak of 631 cases was linked to a salad mix produced by a single Mexican supplier. This was the first major outbreak since the FDA Food Safety Modernization Act was signed into law in 2011, which gave the agency new authority to prevent contamination. The 2018 season saw 2,299 cases across 33 states, with outbreaks linked to vegetable trays from a Wisconsin supplier and cilantro from two Mexican farms. The 2019 season set a new record with 2,408 cases, including a large outbreak linked to basil from a Florida farm. These outbreaks prompted the FDA to issue import alerts for cilantro from specific Mexican states and to conduct on-farm investigations. The COVID-19 pandemic reduced travel and disrupted food supply chains, but cyclosporiasis cases remained elevated in 2020 (1,241 cases) and 2021 (1,225 cases). In 2022, cases dropped to 1,141, and in 2023, preliminary data showed about 1,200 cases. The long-term trend shows a baseline of roughly 1,000 to 1,500 cases per year since 2018, with periodic spikes. Climate change is expected to affect transmission, as Cyclospora oocysts survive longer in warm, humid conditions.