Short Stuff: Cyclospora

In the summer of 2026, more than 28,000 people in the United States were sickened by a parasite most Americans had never heard of: cyclospora. Two people died. The outbreak was traced back to a supplier called Taylor Farms de Mexico, which provided ingredients to Taco Bell and other chains. By August, the case count had already tripled from a month earlier, making this the largest cyclospora outbreak in recorded history — and the third-largest foodborne outbreak ever in the U.S. But the actual number of cases is likely far higher, because most people who get sick never get tested for this particular pathogen.

What Cyclospora Actually Is

Cyclospora cayetanensis is not a bacteria or a virus. It is a protozoan parasite, and humans are its only known host. The first documented human case was in Papua New Guinea in 1978. The first U.S. outbreak came in 1995, in Chicago, with just 23 cases linked to Guatemalan raspberries. Since then, small summer outbreaks have occurred regularly, but nothing on this scale.

The parasite exists in water — rivers, lakes, drinking water, even swimming pools — and it thrives in the crevices of berries and leafy greens, where rinsing alone cannot dislodge it. It spreads through human sewage. If someone with cyclospora does not wash their hands properly, or if sewage-contaminated water is used on crops, the parasite moves to the next host.