The largest recorded cyclospora outbreak in United States history, tied to contaminated iceberg lettuce grown in central Mexico, has now reached nine states, federal health officials confirmed in a Friday briefing.
The Centers for Disease Control and Prevention (CDC) updated its case count this week, adding Illinois, Kansas, Oklahoma, and Pennsylvania to the list of states reporting infections linked to the produce. Indiana, Kentucky, Michigan, Ohio, and West Virginia had previously documented cases connected to the same supply chain. Separate cyclospora outbreaks across 41 states, likely stemming from multiple unrelated sources, have pushed the total national case count past 11,000 since mid-May, according to CDC tracking data.
Michigan remains the epicenter of the outbreak tied to lettuce, with state health officials announcing Friday that confirmed and probable infections there have climbed above 8,100. Affected residents who spoke with the BBC described the illness as debilitating, with one person calling it “the most painful thing I’ve ever been through in my life.” The cyclospora parasite causes the gastrointestinal infection cyclosporiasis, which is marked by severe, sudden explosive diarrhea and other abdominal symptoms.
In response to the ongoing outbreak, the CDC issued a renewed public warning Friday advising consumers to avoid eating recalled iceberg lettuce from major U.S. food supplier Taylor Farms, which sources the product from central Mexico. The company initiated a voluntary full recall of its central Mexican-sourced iceberg lettuce on July 17, saying the move was made “out of an abundance of caution” to protect public health.
Last weekend, investigators from the U.S. Food and Drug Administration (FDA) announced that a sample of Taylor Farms iceberg lettuce had tested positive for cyclospora, only to walk back the claim days later, clarifying the result was a false positive. This misstep underscores the complexities of tracing the parasite, which public health experts say presents unique investigative challenges.
Health specialists who spoke to the BBC explained that one of the biggest barriers to identifying a consistent source of the outbreak is the pathogen’s long incubation period. Symptoms of cyclosporiasis often do not appear until one to two weeks after a person ingests the parasite, making it hard for investigators to retrace patients’ food consumption histories and spot common contaminated sources.
Wade Syers, a food safety and security expert at Michigan State University, told the BBC that the investigation into the multistate outbreak linked to iceberg lettuce will likely be a months-long process rather than a quick resolution. “For Cyclospora, it’s not unusual for the picture to become clearer a couple of months after the first illnesses occur,” Syers said in a Friday email. “Because these investigations are unfortunately more likely to be marathon investigations rather than a quick sprint.”