A parasite outbreak is driving a lot of summer diarrhea. Here's the Cyclospora plan. (2026)

The short version

The CDC is tracking an unusually large rise in domestically acquired cyclosporiasis, an intestinal illness caused by a microscopic parasite called Cyclospora. Since May 1, 2026, the agency has received reports of 1,645 lab-confirmed cases across 34 states. Of the people with available information, 141 were hospitalized and none had died. The CDC is also aware of more than 5,100 additional reports that still need review, so the true number is likely higher. 1

That sounds alarming, but it does not mean there is a confirmed contaminated food that everyone needs to avoid. The CDC and FDA say the current investigation is still trying to identify sources, and officials have not named a food for consumers to stop buying. The useful response right now is boring but effective: handle fresh produce carefully, and do not ignore watery diarrhea that keeps going or comes back. 2

What Cyclospora actually is

Cyclospora gets into your body when you swallow food or water contaminated with infected stool. In the U.S., past outbreaks have often involved fresh produce, but the source of this year's clusters has not been confirmed. The CDC is investigating multiple clusters, including one linked across Michigan, Ohio, West Virginia, and Kentucky, while continuing to look at several produce items. 2

This is also not the same as catching a stomach bug from sitting next to someone. The parasite generally needs one to two weeks outside the body to become infectious, so direct person-to-person spread is unlikely. That is why the current concern is contaminated food or water, not casual contact with a sick roommate. 3

The symptom pattern to know

Symptoms usually start about a week after exposure, but the window can be as short as two days or as long as two weeks or more. The classic symptom is frequent, watery diarrhea. You may also get:

Stomach cramps, bloating, or a lot of gas
Nausea or loss of appetite
Fatigue and sometimes weight loss
Vomiting, body aches, headache, or a low-grade fever

The annoying part is the timeline. Without treatment, symptoms can last from a few days to a month or longer, and the diarrhea can improve before returning. Fatigue can also stick around after the stomach symptoms settle. 4

So if you have one rough day after a questionable meal and then bounce back, that is not a reason to assume you have Cyclospora. If watery diarrhea is still happening after a couple of days, keeps relapsing, or comes with pronounced fatigue and appetite loss, it is worth getting evaluated.

Your practical produce routine

You do not need to stop eating salads, fruit, or vegetables based on the current information. Use this routine instead:

Wash your hands with soap and water before and after handling produce.
Rinse fruits and vegetables thoroughly under clean running water before eating, cutting, or cooking them, even if the package says pre-washed.
Scrub firm produce such as cucumbers and melons with a clean produce brush. Cut away bruised or damaged areas.
Refrigerate cut, peeled, or cooked produce within two hours.
If you cook produce, the CDC said heating it to at least 158 F (70 C) kills the parasite.

Washing lowers risk, but it is not a magic reset button. The CDC says routine chemical sanitizing may not kill Cyclospora, and officials have not identified a specific food to avoid in this investigation. Follow actual food-safety alerts if they are issued, rather than viral posts naming a random ingredient. 5 2

What you can do at home

If you have diarrhea but can drink and do not have red-flag symptoms, focus on replacing both fluid and electrolytes. Water, broth, an oral rehydration solution, or a drink containing electrolytes can help. Take smaller, frequent sips if nausea makes a full glass feel impossible. 6

Do not assume an over-the-counter anti-diarrhea product will fix the cause. For confirmed cyclosporiasis, the CDC lists the prescription antibiotic trimethoprim-sulfamethoxazole, also called TMP-SMX, as the treatment of choice. A clinician needs to decide whether it is appropriate for you, especially if you are pregnant, have a medication allergy, or have a weakened immune system. 7

When you contact a clinician, mention the possibility of Cyclospora if your diarrhea is prolonged or keeps returning. Testing for this parasite is not automatically included in every routine stool test, so a provider may need to request a specific test. 1

When it is more than a wait-and-see problem

Get medical help promptly if you have any of these:

Signs of dehydration, such as extreme thirst, a dry mouth, much less urine, dark urine, dizziness, or feeling unusually weak
Frequent vomiting that prevents you from keeping fluids down
Blood, pus, or black, tar-like stool
Severe abdominal or rectal pain
A high fever, confusion, or a noticeable change in your mental state
Six or more loose stools in a day, or diarrhea lasting more than two days

Those signs can point to dangerous dehydration or another problem that needs treatment, not just an annoying summer stomach issue. People who are pregnant, taking antibiotics, older than 65, or immunocompromised should contact a clinician sooner if diarrhea starts. 8

Bottom line

The current Cyclospora numbers are high enough to pay attention to, but not a reason to panic or ban a whole category of food. Rinse fresh produce under running water, keep cut produce cold, and watch the timeline if you get sick. A lingering or relapsing case of watery diarrhea is the moment to stop guessing, ask about specific Cyclospora testing, and replace fluids before dehydration becomes the bigger problem.

A parasite outbreak is driving a lot of summer diarrhea. Here's the Cyclospora plan.