US faces record Cyclospora outbreak linked to iceberg lettuce, with over 25,000 cases

A widespread outbreak of the parasitic illness Cyclospora has sickened more than 25,000 people across the United States, with health officials identifying iceberg lettuce as a significant source of infection. The Centers for Disease Control and Prevention (CDC) confirmed the outbreak has now spread to at least 15 states.

Initial investigations focused on lettuce served at a fast-food chain, but the probe shifted to Taylor Farms, a company that subsequently recalled iceberg lettuce grown in central Mexico. This recall highlights the challenges in tracing and containing foodborne illnesses, especially those caused by less common pathogens.

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It can take several weeks from the time a person is exposed to the parasite until the first symptoms appear. The parasite is harder to analyze in the laboratory, and it also takes a lot of time to interview all the sick people.

Experts note that controlling Cyclospora outbreaks is particularly difficult. Symptoms can take weeks to appear after exposure, complicating efforts to pinpoint the source and interview affected individuals. Dr. Juan Luis Marquez, a public health professor at the University of Michigan, emphasized that a shortage of staff at all levels of public health further hinders rapid response capabilities.

This year's outbreak has surpassed previous records, with over 25,000 cases reported compared to around 4,700 in 2019, the previous worst year. The FDA is monitoring five separate Cyclospora outbreaks, with the one linked to Mexican lettuce being the largest and most severe. Cyclosporiasis, caused by a microscopic parasite spread through contaminated food and feces, typically occurs in warmer months and causes severe diarrhea. The long incubation period distinguishes it from more common bacterial food poisonings, making timely identification of the infection source a significant hurdle for both patients and medical professionals.

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There has been a reduction in staff at all levels of public health – federal, state, and local – so there are fewer resources and capacities for rapid response overall.