WASHINGTON — Thousands of people across the country have been infected with a parasite that causes severe diarrhea.
National health experts have still not pinpointed a specific cause.
The cyclospora parasite is often transmitted through fresh produce or water that has been contaminated with feces.
Earlier this week, Washington reported 22 provisional cases, meaning they still need to be officially confirmed. A majority were contracted abroad, according to the state’s health department.
The Centers for Disease Control and Prevention (CDC) has reported fewer than 10 cases in Washington that are officially confirmed.
Washington health officials have said we’re not seeing an atypical rise in the state right now.
The CDC has reported nearly 7,000 cases across the country, a figure that includes both confirmed cases and cases that still need to be officially confirmed.
“To have an outbreak of 7,000 and we’ve still not stopped counting is pretty unusual,” said Seattle-based food safety attorney Bill Marler.
Marler noted that historically, infections from cyclospora were typically from imported foods. The last few years, he says, we’ve been seeing more outbreaks within the U.S.
On Tuesday, Federal health officials confirmed the last few years have seen more cases tied to both domestic and imported produce.
Health officials have not determined a single source of the outbreak, and federal officials have said the outbreaks across the country might not all be linked.
Michigan has seen the highest number of confirmed cases. State officials there have said they are exploring a possible connection to lettuce and salad greens, though they’re not ruling any foods out yet.
State officials there are urging consumers to buy whole heads of lettuce, instead of bagged lettuce and pre-mixed salad kits. They’re urging shoppers to remove the outer layers of the lettuce and wash the rest thoroughly.
To stay safe, the CDC recommends washing your hands with soap and water before handling food. Wash fresh produce thoroughly under running water.
Some experts have also recommended washing produce in a solution of three parts water and one part vinegar to help remove germs.
Washing alone will not eliminate the infection risk, though.
To kill the infection, cook your produce. The CDC recommends heating food to 158°F or higher.
Because the parasite can spread from fecal matter to water, experts are urging anyone with gastrointestinal issues to avoid pools or splash pads. Cyclospora is resistant to chlorine.
If you’re experiencing symptoms, go to a doctor and request a test for the infection.
Experts have warned that the true number of causes is likely higher than we know.
The infections can be difficult to track because of how long it can take from exposure to become infected. The CDC says infection usually follows about one week after exposure, but can range from two days to two weeks or more.
CBS News reports the outbreak comes about a year after the the CDC scaled back some monitoring of the parasite. In July 2025, the CDC narrowed reporting requirements for cyclospora, making it optional as opposed to mandatory.
The agency was asked about the move on Tuesday, and said that reporting change pertained to a program that monitors trends over time.
“The data that we have for cyclosporiasis for this outbreak is the same as we’ve had for all of the other seasons,” said Dr. Gwen Biggerstaff, the deputy director of the CDC’s division of foodborne, waterborne, and environmental diseases. “We use the same systems and the same processes. So that is unchanged.”
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