Cyclosporiasis, a little-known but disruptive illness that causes diarrhea, can be found anywhere from salad bars to swimming pools and some overseas vacations.
The Mountain West hasn’t experienced the virus with the same severity as people living in the Midwest, but they are beginning to see cyclosporiasis in their communities.
- Arizona: 19 cases
- Colorado: 178 cases
- Idaho: 4 cases
- Nevada: 6 cases
- New Mexico: 5 cases
- Wyoming: 5 confirmed cases, 1 case remains under investigation
- Utah is investigating a handful of cases: 1 case has been confirmed as an in-state case from May 1
Those numbers are from federal, state and local officials. The number of cases in Utah may number in the single digits and have not been confirmed as cyclosporiasis. They remain under investigation.
Health officials in several Mountain West states attribute most of the illnesses to out-of-state and international travel.
Sarah Shrum Davis, an infectious disease epidemiology supervisor with the New Mexico Department of Health, said a large outbreak is centered in the Midwest, with many cases linked to pre-packaged lettuce. Historically, outbreaks have also been traced to other fresh produce: herbs like cilantro, various berries, and other fruits and vegetables. That’s why Shrum Davis emphasizes thoroughly washing produce and following basic food safety rules.
In New Mexico, however, Shrum Davis said the situation is relatively calm.
“The state has recorded five cases in 2026, in line with its typical annual average of eight to nine. All of the patients reported recent international travel, suggesting they were infected abroad, likely in tropical regions where cyclospora is more common,” she said, “So far, there’s no sign of a local outbreak or contaminated produce distributed in the state.”
Cyclospora parasitic infections tend to peak from May through August, when fresh produce is abundant, travel increases, and more people are swimming or visiting water parks, Shrum Davis explained. The parasite is unusually tolerant of chlorine, raising concerns about pools and splash pads if someone with diarrhea swims. Still, Shurm Davis notes that many factors — from climate and weather patterns to global food distribution — shape these outbreaks, and teasing out the role of climate change remains complex.
For now, public health advice is straightforward: wash fruits and vegetables, practice good hand hygiene, stay out of pools when you’re sick, and seek care if severe diarrhea persists. And while some parasites can jump between species, the strain Cyclospora cayetanensis infects only humans — meaning pets are in the clear.
The Food and Drug Administration says the source of the outbreak is unknown, but recommends that people avoid iceberg lettuce grown or processed by Taylor Farms in Mexico, as the agency continues to investigate.