Parasitic Outbreak Across 34 US States Leaves Health Officials Searching for Source

Nearly 7,000 people across 34 US states have contracted cyclosporiasis, a parasitic infection that causes frequent, watery, and explosive diarrhea, according to the Centers for Disease Control and Prevention. The outbreak's source remains unknown, complicating public health efforts to contain the spread. Michigan has been hardest hit with over 3,300 confirmed cases, followed by New York state, while Ohio, West Virginia, and Kentucky have each recorded hundreds of additional infections.

What Makes This Outbreak Difficult to Contain

Health officials face extraordinary challenges in tracing cyclosporiasis because the parasite behaves differently than other foodborne pathogens. Infected individuals typically fall ill between one and two weeks after exposure, making it nearly impossible to recall what contaminated food or water they consumed. Most other food-related illnesses manifest within hours, allowing investigators to identify sources quickly.

Steven Manderach, executive director of the Association of Food and Drug Officials, described the detection difficulty in stark terms: "This isn't like detecting a needle in a haystack. It's like detecting a microscopic portion of a needle in a haystack." Testing food for the parasite requires washing truckloads of produce to extract cyclospora organisms, then analyzing the runoff—a labor-intensive process far more complex than screening for common pathogens like salmonella or E. coli.

Geographic Spread and Current Status

The outbreak spans multiple regions, with concentrations in the Midwest. Michigan and Ohio reported more than 3,000 combined cases by the most recent count, with over 1,000 diagnoses occurring within just two weeks. Indiana, Texas, and New Jersey also report significant case numbers. The CDC confirmed 1,645 cases as of its latest update, with an additional 5,100 suspected cases still under investigation. The actual infection count is likely higher, as some people recover without seeking medical attention or undergoing testing.

Past cyclosporiasis outbreaks have been linked to raw produce, prompting the CDC to advise the public to thoroughly wash fruits and vegetables and avoid certain items like raspberries. Cooking vegetables can kill the parasite, though the agency has not identified which specific produce or supplier is responsible for the current outbreak. Public health experts believe multiple contamination points within the food supply may be involved, further complicating investigation efforts.

Systemic Challenges in Response

Some epidemiologists have pointed to budget constraints affecting federal health agencies as a contributing factor to the delayed outbreak response. Jodie Guest, senior vice chair of epidemiology at Emory University's Rollins School of Public Health, emphasized that limited resources hamper the investigative process. Despite these obstacles, no deaths have been reported, though 141 patients have required hospitalization. The CDC anticipates case numbers will continue rising as data collection proceeds and new infections are identified and confirmed.