Summary (tl;dr)

A multi-state outbreak of cyclosporiasis, an intestinal illness causing severe gastrointestinal symptoms like "explosive diarrhea," is currently trending, with a significant surge in cases in Michigan and Louisiana, linked primarily to contaminated fresh produce such as salad greens and berries.

Essential Background

Cyclosporiasis is an intestinal infection caused by the microscopic parasite Cyclospora cayetanensis. It is typically transmitted by consuming food or water contaminated with human feces containing the parasite. Unlike many foodborne illnesses, it does not usually spread directly from person to person. Symptoms, which can include watery diarrhea, stomach cramps, nausea, and fatigue, usually appear about a week after exposure and can last for days or even weeks if untreated. Outbreaks are often linked to raw produce like berries, basil, cilantro, and leafy greens, and tend to increase during warmer months.

The Full Story

Public health officials across the United States are currently investigating a widespread cyclosporiasis outbreak, with Michigan identified as an epicenter, reporting over 2,640 cases across 43 counties. In Michigan, health officials suspect lettuce and other salad greens as a potential source, prompting Taco Bell to temporarily remove several fresh ingredients, including lettuce, guacamole, pico de gallo, and cilantro-onion blend, from some locations as a precaution. Louisiana has also seen a significant increase, confirming 36 cases statewide this year, with five hospitalizations. While Colorado has recorded 90 cases since January, most are linked to international travel and are not part of the current domestic multi-state outbreak. Other states, including Ohio (364 cases), New York (470 cases), and Texas (48 cases), have also reported a rise in infections. The Centers for Disease Control and Prevention (CDC) has reported 843 confirmed domestic cases across 31 states since May 1, 2026, and is aware of over 1,500 additional cases requiring further analysis, noting that their tracking has been impacted by changes implemented in 2025. Investigations are ongoing to pinpoint the specific contaminated food source, which can be challenging due to the parasite's incubation period and the difficulty in tracing its origin.

Why It Matters

This outbreak highlights the persistent risk of foodborne parasitic illnesses, especially from fresh produce, and the challenges in controlling them. Cyclosporiasis can lead to prolonged and severe illness, with symptoms like "explosive diarrhea" significantly impacting daily life and potentially requiring hospitalization due to dehydration. A critical concern is that routine washing of fruits and vegetables does not reliably remove or kill the Cyclospora parasite, as it is protected by a resilient outer shell (oocyst) that resists water and chemical sanitizers. The only effective way to destroy the parasite is through thorough cooking, baking, or boiling food to at least 158 degrees Fahrenheit (70 degrees Celsius). This makes raw produce like salads and berries particularly vulnerable to contamination and difficult to safely prepare, emphasizing the need for consumers to be vigilant about food safety practices and for public health officials to identify and address contamination sources in the food supply chain.

Geographic Location

• Michigan, United States (epicenter of multi-state Cyclospora outbreak, lettuce/salad greens suspected source)
• Louisiana, United States (surge in cyclosporiasis cases)
• Colorado, United States (increased cyclosporiasis cases, primarily linked to international travel, not the current multi-state domestic outbreak)
• Ohio, United States (significant number of cyclosporiasis cases)
• New York, United States (significant number of cyclosporiasis cases)
• Texas, United States (reported cyclosporiasis cases as part of an outbreak)