Source of diarrhea-inducing parasite in Idaho, US found. What’s causing outbreak?
Health officials now have a clear answer about the origin of cyclosporiasis cases across Washington state and the nation.
It’s being driven by contaminated lettuce and salad greens, according to the U.S. Centers for Disease Control and Prevention.
The CDC and state health departments, including Michigan’s Department of Health and Human Services have moved from identifying a “potential source” to a more definitive link, pointing directly to leafy greens as the primary vehicle for the Cyclospora parasite.
However, officials say other foods cannot be ruled out, and there’s been no specific type, grower or supplier identified as the source for contaminated lettuce.
What Is cyclosporiasis?
Cyclosporiasis is an intestinal infection caused by the protozoan parasite Cyclospora.
Cyclosporiasis is contracted after consuming foods or water contaminated by the microscopic parasite, according to the U.S. Food and Drug Administration.
“Case counts typically rise during spring and summer months,” the CDC said, noting that May 1 to Aug. 31 is considered the annual cyclosporiasis season.
Diarrhea among symptoms of Cyclospora infection
Symptoms typically begin about one week after exposure and can persist for weeks without treatment, health officials say.
The Cyclospora parasite causes “watery, and sometimes explosive, diarrhea and other stomach problems,” according to the Cleveland Clinic.
Other common symptoms include:
- Loss of appetite
- Bloating, including burping and farting
- Extreme tiredness (fatigue)
- Low-grade fever
- Stomach cramps
- Nausea
- Vomiting
How many cases have been confirmed in the US?
Since May 1, the CDC has received reports of at least 1,645 confirmed cases of cyclosporiasis in the United States, resulting in 140-plus hospitalizations,
The federal health agency said it is “aware of more than 5,100 cases that require further analysis to confirm the illness as domestically acquired cyclosporiasis.”
A total of 34 states have reported Cyclospora infections since May 1, according to the CDC.
Based on past trends, federal health experts expect case numbers to continue to rise.
What about Idaho?
As of Tuesday, July 14, there was one confirmed case of cyclosporiasis in Idaho, according to state health officials.
“Idaho is currently investigating one lab-confirmed cyclospora infection in an Idaho resident that traveled outside of Idaho before becoming ill,” AJ McWhorter, Idaho Department of Health and Welfare public information officer, previously told the Idaho Statesman.
Lettuce and salad identified as outbreak culprits
Michigan health officials, which are at the center of a large multistate outbreak in the Midwest, have identified the source of the cyclosporiasis outbreak in their state.
New epidemiological data and traceback investigations have led to leafy greens as the most consistent exposure among affected individuals.
Public health messaging has shifted from “consider other foods” to “avoid or properly handle raw leafy greens,” indicating that the evidence now points decisively to lettuce and related products.
How to prevent getting sick
The FDA recommends following these steps to stay safe during Cyclospora season:
- Discard outer layers of fruits and vegetables
- Rinse all fresh fruits and vegetables under clean running water.
- Use a clean vegetable brush to scrub firm produce.
- Be cautious with pre-washed or pre-cut produce.
- Clean kitchen counter tops, cutting boards and utensils with hot, soapy water.
- Cook produce to a temperature of at least 158 degrees.
You should always wash your hands with warm water and soap for at least 20 seconds before and after handling food, the FDA said.
This story was originally published July 16, 2026 at 11:23 AM with the headline "Source of diarrhea-inducing parasite in Idaho, US found. What’s causing outbreak?."
