The Food and Drug Administration (FDA) reported Monday that several outbreaks of cyclospora with unidentified sources are expanding across the United States. According to the Centers for Disease Control and Prevention (CDC), nearly 14,000 domestically acquired cases of the parasite have been confirmed since May 2026. This figure represents a sharp increase from the approximately 1,180 cases reported during the same period in 2025.
Cyclospora is a parasite that causes intestinal illness, often transmitted through contaminated food or water. While one major outbreak affecting 17 states has been traced back to iceberg lettuce, the FDA is currently tracking seven active investigations. Three investigations have concluded, involving a total of 28 people, but four others remain active without a confirmed source of infection.
Recent data shows that one unidentified outbreak, first reported in early August, has grown to 11 cases, while another reported in late July has increased from 115 to 172 cases. The FDA is conducting traceback investigations to determine the origin of these illnesses. Additionally, the outbreak linked to iceberg lettuce expanded late last week to include Maine and Massachusetts, bringing the total number of cases associated with that specific source to at least 9,480.
A person infected with the parasite may not notice symptoms for several weeks. When symptoms do occur, they typically involve gastrointestinal distress that may require medical intervention, such as antibiotics, antidiarrheal medication, and increased hydration. The CDC noted that the reported numbers likely undercount the true total, as many individuals do not seek testing or hospitalization. Because the parasite is difficult to sequence and symptoms are delayed, investigators often face significant time lags in identifying contaminated products, which can lead to prolonged periods where the source remains unknown to the public.
The knock-on effects include repeated expansions of food recalls, as seen with the recent addition of two New England states to the iceberg lettuce outbreak list. Healthcare providers are being encouraged to monitor patients for symptoms lasting more than two weeks. While two outbreaks have shown growth in the last month, the FDA continues its traceback efforts for five active investigations. No specific deadlines for concluding these investigations were reported, as the timing depends on the success of tracing contaminated food through the supply chain.