Federal health officials have issued an urgent advisory following a dramatic spike in domestically acquired cases of cyclosporiasis, a parasitic stomach illness linked to contaminated food and water.

Since May 1, 2026, the Centers for Disease Control and Prevention (CDC) has confirmed 1,645 domestic cases across 34 states—a massive jump from the 249 cases reported during the same period last year. Health officials are also tracking more than 5,100 additional potential cases that require further analysis.

Of those infected, 141 people (9%) have been hospitalized. No deaths have been reported.

The Scale of the Outbreak

The CDC, the U.S. Food and Drug Administration (FDA), and state health departments are actively investigating multiple multistate outbreaks. This includes one major cluster of more than 400 cases spread across at least four states, suggesting a potential common food source.

Because the infection is historically underdiagnosed and underreported, officials warn that the actual number of illnesses is likely much higher than currently recorded.

What is Cyclosporiasis?

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora.

• How it spreads: People typically contract the parasite by eating contaminated fresh produce or drinking contaminated water. It is not usually spread directly from person to person.

• The Season: Case counts traditionally rise during the spring and summer, with May 1 through August 31 designated as peak season.

• Symptoms: Typically appearing about one week after exposure, symptoms include frequent watery diarrhea, loss of appetite, bloating, stomach cramps, nausea, and fatigue. Without treatment, symptoms can relapse and persist for weeks or even months.

Guidance for Clinicians and Laboratorians

The CDC is urging healthcare providers to maintain a high index of suspicion for patients presenting with prolonged watery diarrhea, even if they have no recent history of international travel.

Crucial Diagnostic Note: Standard stool exams (ova and parasite tests) often fail to detect Cyclospora. Clinicians must specifically request Cyclospora testing or utilize molecular (PCR-based) diagnostic tests.

Confirmed cases are highly treatable with a 7-to-10-day course of the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX).

What Consumers Can Do

To reduce the risk of infection, health officials recommend the following food safety measures:

• Wash all fresh produce thoroughly under clean, running water before eating, cutting, or cooking.

• Do not rely solely on chemical sanitizers, as standard disinfectants may not fully eliminate the hardy Cyclospora parasite.

• Wash “pre-washed” packaged produce as an extra precaution.

• See a healthcare provider immediately if you experience prolonged, severe, or watery diarrhea.