CDC Ends Cyclospora Outbreak Linked to Iceberg Lettuce

The Centers for Disease Control and Prevention (CDC) has officially concluded a multistate outbreak of Cyclospora linked to iceberg lettuce. This outbreak affected a total of 12,883 individuals across 21 states, resulting in 570 hospitalizations and two fatalities.

Newsweek provided detailed mapping of the outbreak cases, explored the outbreak’s cause, and examined other ongoing foodborne outbreaks. The extensive outbreak, one of the largest recorded in the U.S., was traced to iceberg lettuce processed by Taylor Farms de Mexico. On July 17, the company recalled all iceberg lettuce sourced from central Mexico. As of September 11, the CDC confirmed that the affected products are no longer sold in stores or served in restaurants, stating, “At this time, there is no risk of people getting sick with cyclosporiasis from this source.”

The Wider Context of Cyclospora Cayetanensis

These outbreak figures form a segment of an extensive surge in Cyclospora cayetanensis infections. This microscopic parasite causes cyclosporiasis, an intestinal illness. Since May 1, the CDC reported 19,595 laboratory-confirmed cases acquired domestically in 49 states and Washington, D.C.; 1,043 were hospitalized, and two deaths occurred.

The CDC map indicates where patients resided, though it doesn’t specify where they contacted the parasite. Newsweek developed a map highlighting these statistics. Though the outbreak was linked to iceberg lettuce contamination, the precise cause remains under investigation by the Food and Drug Administration (FDA). Multiple separate cyclosporiasis clusters remain under investigation, and federal officials are evaluating other ongoing outbreaks involving pathogens like Salmonella, E. coli, and Listeria.

Tracing the Source of the Cyclospora Outbreak

The iceberg lettuce connection was established through patient interviews and supply chain tracing rather than through direct laboratory tests on recalled produce. The investigation centered on illness reports linked to Taco Bell restaurants. Michigan officials reviewed the dining histories of 190 individuals who reported dining at Taco Bell, with 90% having consumed iceberg lettuce.

FDA investigators traced the lettuce supplied to affected restaurants back to a single company. An initially reported positive lettuce sample was re-evaluated and deemed a false positive. This occurred because the sample did not show true parasite amplification. On July 19, the FDA stated that no confirmed positive samples resulted from product testing.

Investigators have yet to disclose the specific point or contamination mechanism, whether during growing or processing, or through polluted water. The parasite spreads when food or water gets contaminated with human feces, taking 1–2 weeks outside the body to become infectious, making direct person-to-person transmission unlikely.

The FDA conducted inspections and sampling at growing sites and processing facilities in collaboration with Mexican authorities. While the CDC has ended its outbreak response, the FDA’s investigation remains ongoing.

Investigating Other Foodborne Outbreaks

As of September 12, the FDA listed eight active foodborne outbreak investigations involving pathogens aside from Cyclospora. Although some outbreaks were traced to specific foods, many remain unidentified.

• Salmonella Bovismorbificans linked to broccoli sprouts: 22 infections across four states, two hospitalizations, no deaths. Evergreen Fresh Sprouts recalled the implicated products after the strain was found in broccoli sprout samples.
• Salmonella Newport with an unknown source: 109 cases recorded, but no food associated yet. Traceback efforts are ongoing.
• Shiga toxin-producing E. coli and Salmonella Agona linked to sprouts: 55 cases in 15 states, four hospitalized. Alfalfa sprouts from Everything Sprouts identified as one source, but additional illnesses remain unexplained. Several sprout products have been recalled.
• Salmonella I 4,[5],12:i:- with an unknown source: 43 cases reported. FDA started traceback, inspections, and sampling without publicly identifying any implicated food.
• Salmonella Javiana linked to jalapeño peppers: 431 cases, 32 states impacted, 57 hospitalized. Linked to jalapeños from Sinaloa, Mexico, distributed by Coast Citrus Distributors, resulting in recalls of peppers and related products. No deaths reported.
• Listeria monocytogenes with an unknown source: Nine cases reported. Investigators initiated traceback, inspections, and sampling but didn’t identify a food source.
• Salmonella Oranienburg with an unknown source: 99 cases linked. Inspections, sampling, and traceback work underway.
• E. coli O145:H28 linked to frozen blueberries: 17 cases in Florida and Georgia, six hospitalized. GreenWise and Great Value Organic Triple Berry Blend products recalled due to contamination.

Consumers have been advised to check their freezers for frozen blueberries bearing 2028 best-by dates.

Contact Newsweek editor on this story: Edward Pearcey.