Cyclospora: Public Health – Seattle King County issues update

Published 4:38 pm Thursday, July 16, 2026

Public Health – Seattle & King County issued the following information July 16 about a national outbreak of Cyclospora, aka explosive diarrhea:

A national outbreak of Cyclospora—more commonly known by its main symptom, explosive diarrhea—has cases reported in Michigan, Ohio, New York, and many other states. This appears to be a very large outbreak nationally, but here in King County, we have not seen any unexpected increases in cyclosporiasis (the disease caused by Cyclospora) so far. We talked with Ann Shen, the lead for foodborne and enteric disease investigations for Public Health – Seattle & King County, about the current local situation.

Are we getting reports of cyclosporiasis in King County?

We aren’t getting reports of unexpected increases in cases, and there’s no evidence that the outbreak affecting other states is impacting King County so far.

But every year, a small number of King County residents are diagnosed with cyclosporiasis, and this year is no different. Most people are exposed during international travel, but we generally see a few residents with no out of state travel, who likely got sick from the parasite from a local source.

You said “parasite.” Is that what causes the explosive diarrhea?

Yes, a microscopic parasite called Cyclospora lives in the human gut and can spread through food or water contaminated with human feces. It’s a tough parasite that can survive on produce and can’t be killed by typical cleaning methods, such as rinsing or washing. Vigorously scrubbing or removing the fruit or vegetable skin can help further reduce risk.

How is this gastrointestinal illness different from others, like norovirus?

Norovirus is a common virus with similar symptoms, but it spreads easily and quickly from person to person and symptoms generally last only a day or two. Cyclospora are not spread from person to person and symptoms can last more than a week—the explosive diarrhea can come and go for weeks to a month or longer. You can get antibiotics that can target Cyclospora even though it’s not a bacteria, but antibiotics don’t work for norovirus.

Like norovirus, symptoms you may get from Cyclospora can be terribly unpleasant and disrupt your life, but they are generally mild. However, some groups are more vulnerable to serious illness and that can lead to hospitalization. Older adults, young children, anyone who is pregnant, and people who have weakened immune systems may be at greater risk.

If there aren’t any cases linked to the national outbreak here, is there anything King County residents should do to avoid Cyclospora?

Contaminated produce is the likely source of the national outbreak, and disease investigators throughout the country are trying to pinpoint the source, but that hasn’t been confirmed yet. Since we don’t yet know what has caused the national outbreak—and so far there are no linked cases in King County—we aren’t advising people to throw out otherwise good produce here. We’re also not currently recommending that people change their normal shopping routines.

It’s always a good practice to wash your hands and any fresh produce thoroughly under running water before eating, cutting or cooking, but it won’t completely eliminate the risk of getting sick.

If you want to reduce the risk of getting sick from raw or undercooked produce—like if you have a weakened immune system or you’re preparing food for young children—you can cook it. Heating food to an internal temperature of 158°F (70°C) or higher is effective at killing the parasite.

What about salad greens and lettuce that we are hearing so much about?

In Michigan, public health experts shared they don’t have a definite product identified, but early information has shown lettuce as a common product that comes up during their investigation. That’s why there are some recommendations in other states for avoiding bagged lettuce or salad kits.

While we are not recommending avoiding particular items at the moment, for people who have a weakened immune system or who are concerned about risk, it’s reasonable to not eat foods that have been previously known to have Cyclospora, like bagged salads, raspberries and packaged fresh herbs.

For more information

More information about cyclosporiasis and the national outbreak: https://www.cdc.gov/cyclosporiasis

Source: Public Health Insider