CDC Declares the Nation’s Largest Cyclospora Outbreak Over After Nearly 13,000 Illnesses

The Centers for Disease Control and Prevention has closed the book on the largest multistate Cyclospora outbreak ever recorded in the United States, tying the parasite to contaminated shredded iceberg lettuce that sickened 12,883 people across 21 states.

The agency issued its final update on Sept. 11, saying new infections tied to the outbreak had slowed to a trickle and that the recalled lettuce was no longer sitting on shelves or moving through restaurant kitchens.

Along the way, the outbreak sent 570 people to the hospital and killed two, both in Michigan. Even with the outbreak officially over, the FDA says it hasn’t finished figuring out how the contamination got into the food supply in the first place, which means the broader investigation is still very much alive.

For a parasite that most Americans have never heard of, this year’s numbers turned into one of the more sobering food-safety stories of the summer.

Where the contamination started

Investigators traced the source to shredded iceberg lettuce processed at a Taylor Farms facility in central Mexico, operating under the name Taylor Farms de Mexico. Health officials leaned on a mix of epidemiological interviews and traceback records to connect scattered illnesses back to that single supply chain.

Many of the people who got sick told investigators they had eaten at Taco Bell locations, which had been buying shredded lettuce from the affected supplier, while others encountered the product through grocery stores and other food-service channels.

Taylor Farms recalled the lettuce on July 17, but by the time the CDC closed its investigation, the recalled batches had already blown past their best-by dates. That timing detail matters because it’s part of why the CDC felt comfortable calling the outbreak finished: the product causing the problem had aged out of the supply chain on its own.

Illnesses connected to this outbreak began cropping up in Jun and kept appearing into Aug, tracking the arc you’d expect once contaminated produce enters distribution and then gets pulled. At its worst point, more than 1,000 new infections were being reported in a single day, a pace that alarmed state health departments watching their case counts climb by the hundreds week over week.

By August, that daily count had collapsed to fewer than two new cases a day, according to the CDC’s own reporting on its final update. That kind of drop-off is usually the clearest signal epidemiologists have that a specific contamination event has run its course, since it shows the source of exposure has actually left the market rather than just being reported less.

What Cyclospora actually is

Cyclospora is a parasite responsible for an intestinal infection called cyclosporiasis, and people typically pick it up by eating food or drinking water that’s been contaminated with it. Symptoms tend to run toward watery diarrhea, fatigue, and a loss of appetite, along with other gastrointestinal complaints that can range from mildly annoying to genuinely debilitating.

Some people ride it out without ever seeing a doctor, which is part of why the CDC has long suspected that official case counts understate how many people actually get infected each year. On top of that, testing and reporting delays mean it can take roughly six weeks from when someone first feels sick to when their case shows up in federal surveillance data, which is a big part of why outbreak numbers tend to creep upward for weeks after they’re first reported.