MYNORTHWEST NEWS

Parasite causing ‘explosive’ diarrhea surges nationwide, but King County cases remain at normal levels

Jul 10, 2026, 4:41 PM | Updated: Jul 14, 2026, 3:44 pm

parasite explosive diarrhea oregon...

A microscopic look at cyclosporiasis. (Photo courtesy of the CDC)

(Photo courtesy of the CDC)

The microscopic parasite Cyclospora, which has been reported to cause explosive diarrhea, is surging across the U.S., but the number of cases in King County remains at normal levels.

Cyclospora causes a gastrointestinal disease called cyclosporiasis, with symptoms including watery diarrhea, loss of appetite, and weight loss, according to the U.S. Centers for Disease Control and Prevention (CDC).

There have been 15 cases among King County residents, only one of which was exposed to the parasite locally, Public Health – Seattle and King County confirmed to MyNorthwest. Two cases were reported in April, while the other 13 were reported from June to July, including the person who was locally exposed.

Public Health said these numbers are consistent with previous years, with 90% of King County residents diagnosed from June to August and being linked to travel outside the U.S.

“While cases acquired locally are much less common, we do report 1-3 cases per year among residents who do not report traveling outside of Washington,” a Public Health spokesperson stated.

Meanwhile, 22 provisional cyclosporiasis cases, meaning they have been reported but not yet finalized, have been reported statewide between Jan. 1 and June 30, according to the Washington State Department of Health (DOH). Seventeen of those cases occurred between May 1 and June 30, but 15 were acquired during international travel to countries where the parasite is common.

No food safety alerts issued for Washington produce

The parasite is common in tropical and subtropical parts of the world but can sometimes be seen in foods in the U.S.

Officials said the DOH has not issued any food recalls or safety alerts regarding produce distributed in Washington, as there has not been any atypical increase in cyclosporiasis.

Large-scale cyclosporiasis outbreaks have been linked to commercially packaged and imported produce, such as pre-packaged salad mixes, berries, and herbs, officials said. However, they noted any raw produce that is exposed to contaminated water or inadequate sanitation can pose a threat.

“The best controls for Cyclospora are generally at the farm or processing level before produce enters a retail food establishment, and include preventing exposure to contaminated water,” Public Health stated. “At the retail level, when serving fruits or vegetables in a ready-to-eat form, retail food establishments are required to thoroughly rinse produce under running water before any cutting/processing is done. This helps to remove any soil or other contaminants that could harbor pathogens, including cyclospora.”

Diarrhea-causing parasite hits 31 states

Seven cases of cyclosporiasis were reported in Oregon in June and seven in May, as shown by Oregon Health Authority data.

The parasite has hit 31 states, affecting the Midwest and East Coast the hardest. Michigan has seen more than 1,000 cases as of Wednesday, according to a data map by KOIN. However, the media outlet noted the data includes all cases reported this year and may not be part of the CDC’s investigation.

Illinois, New York, Ohio, and North Carolina have all reported 100 to 500 cases, as shown on KOIN’s map.

The CDC’s numbers differ from those of specific state health departments as the CDC works to confirm reported cases.

“The true number of people sick with cyclosporiasis was likely higher than the number reported,” the CDC stated. “This is because some people recover without medical care and are not tested for Cyclospora.”

At least 843 people reported sick from parasite in U.S.

As of Thursday, at least 843 cases of cyclosporiasis were reported in the U.S., according to officials, with 86 people hospitalized. The people became sick after eating food in the U.S. and did not report any travel during the two weeks before they got sick.

On average, 10% of patients require hospitalization, according to NBC News.

The majority of people sick were female at 59%, while ages ranged from 5 years old to 88 years old.

No deaths have been reported.

Taco Bell pulls certain ingredients

Several Taco Bells across the country have pulled fresh produce from the menu amid the outbreak, Food Safety News reported Thursday. Taco Bell has posted notices at some locations stating that they can’t serve lettuce, pico de gallo, guacamole, cilantro, or onions.

Those who suspect they were sickened with cyclosporiasis are recommended to see their health care providers, who can test them for the disease. CDC asks health care providers to report positive tests to their local health departments.

To help prevent foodborne illness related to fresh produce, Public Health advises washing hands with soap and water, washing all produce, scrubbing firm fruits and vegetables, cutting away any damaged or bruised areas, and refrigerating cooked fruits and vegetables as soon as possible. Officials also advise avoiding contaminated food and water and thoroughly cooking harder-to-wash produce, such as raspberries, to reduce the risk of cyclosporiasis.

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Parasite causing ‘explosive’ diarrhea surges nationwide, but King County cases remain at normal levels