UPDATE (July 17): The outbreak is still growing. New clusters continue to be reported — including in Buncombe County, North Carolina — as the CDC and state health departments trace cases across the country. The parasite spreads through contaminated fresh produce, not person-to-person. Full state list, symptoms and safety guidance below.

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The CDC is investigating a fast-growing outbreak of cyclosporiasis — an intestinal illness caused by the microscopic Cyclospora parasite — that has now reached 18 US states. Federal officials counted 145 domestically acquired cases across 17 states between May 1 and June 16, 2026, with 20 people hospitalized and no deaths. Since then, Michigan health officials have reported 572 cases in that state alone, pushing the combined total above 700. Here's what the parasite is, the symptoms to watch for, which foods investigators are looking at, and how to protect your family.

What Is a Parasite Outbreak? Meet Cyclospora

Cyclosporiasis is caused by Cyclospora cayetanensis, a parasite so small it can only be seen under a microscope. People get sick by eating food or drinking water contaminated with the parasite — most often fresh produce. Unlike a stomach bug, it does not usually spread person-to-person, which is why investigators focus on tracing food.

The infection has earned an unpleasant nickname in headlines — The Guardian described it as the parasite behind cases of "explosive" diarrhea — because the illness's defining symptom is frequent, urgent, watery diarrhea that can drag on for weeks.

What States Have the Parasite Outbreak?

According to the CDC's surveillance data and state health departments, cases in 2026 have been reported in:

  • Hardest hit: New York and Michigan (Michigan alone: 572 reported cases, per state officials)
  • South: Texas, Louisiana, Florida, Georgia, Tennessee, North Carolina, Virginia
  • Midwest: Illinois, Wisconsin, Ohio, Michigan
  • Northeast: New York, New Jersey, Pennsylvania, Connecticut, Massachusetts
  • West: Colorado, Alaska

Patients have ranged in age from 5 to 86 years old (median 42), and 61% have been female. Another 45 US travelers picked up the infection abroad. The median illness onset was May 13, and case counts have kept climbing through early July.

Parasite Outbreak Symptoms — and When to See a Doctor

  • Frequent, watery diarrhea (the hallmark symptom)
  • Loss of appetite and weight loss
  • Stomach cramps and bloating
  • Nausea (vomiting is less common), fatigue, low-grade fever

Symptoms typically begin 2 to 14 days after exposure (about a week on average) and can last from a few days to more than a month. A distinctive warning sign: symptoms may fade and then come back if the infection isn't treated. If you've had watery diarrhea for more than a few days — especially after eating fresh produce or traveling — the CDC advises seeing your healthcare provider, who can order a stool test.

What Food Caused the Parasite Outbreak?

Investigators haven't confirmed a single source yet. The CDC says there is currently no evidence that one multistate outbreak links all the cases — instead, the agency is working with the FDA and state health officials to trace several separate clusters.

History gives strong clues, though. Past US cyclosporiasis outbreaks have been repeatedly tied to imported fresh produce, including raspberries, basil, snow peas, mesclun lettuce and cilantro. Because the parasite arrives on food, recalls or specific produce warnings could follow as the trace-back work continues — we'll update this page if a source is named.

How to Protect Your Family

  • Wash your hands with soap and water before handling any produce.
  • Rinse all fruits and vegetables under running water, and scrub firm produce (like melons and cucumbers) with a clean brush.
  • Refrigerate cut produce within two hours.
  • Cooking kills the parasite — washing lowers the risk but may not remove Cyclospora completely, so cooked produce is the safest option for vulnerable family members.

Is There a Treatment?

Yes. Doctors typically treat cyclosporiasis with the antibiotic combination trimethoprim-sulfamethoxazole (sold as Bactrim or Septra), per CDC clinical guidance, along with rest and plenty of fluids to stay hydrated. Most people recover fully — the 2026 cases have caused hospitalizations but no deaths. Diagnosis requires a specific stool test, so mention recent produce or travel history to your doctor.

Frequently Asked Questions (FAQ)

What is the parasite outbreak in the US right now?

A surge of cyclosporiasis — an intestinal illness from the Cyclospora parasite, usually spread through contaminated fresh produce. The CDC counted 145 domestic cases across 17 states (May 1–June 16), and Michigan has since reported 572 cases on its own, bringing the total above 700 across 18 states.

What are the symptoms of the parasite outbreak?

Frequent watery diarrhea, appetite and weight loss, cramps, bloating, nausea, fatigue and low-grade fever — starting 2 to 14 days after exposure and lasting days to over a month. Symptoms can return if untreated.

What states have the parasite outbreak?

Alaska, Colorado, Connecticut, Florida, Georgia, Illinois, Louisiana, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Texas, Virginia and Wisconsin — with New York and Michigan hardest hit.

What food caused the parasite outbreak?

No single food has been confirmed for the 2026 cases yet. Historically, outbreaks have been linked to imported fresh produce such as raspberries, basil, snow peas, mesclun lettuce and cilantro. The CDC and FDA are tracing several clusters.