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July 15, 2026

Domestically acquired Cyclosporiasis cases in multiple US states

➜ This health advisory is also available in PDF format (234 KB)

Current situation

Since May 1, 2026, the Centers for Disease Control and Prevention (CDC) has received 1,645 confirmed domestic cases of cyclosporiasis and is reviewing over 5,100 additional cases that may have also being acquired in the United States. CDC, the Food and Drug Administration (FDA), and state and local health departments are investigating several multistate outbreaks of Cyclospora infections to identify the sources of illness. In Washington State, cyclosporiasis is a reportable condition. Cases identified since May 2026 have been primarily linked to travel, and, to date, no outbreak related cases have been detected in Washington.

Actions requested

  1. Identify

    • Consider cyclosporiasis in patients presenting with prolonged or relapsing watery diarrhea, particularly during the May–August cyclosporiasis season, even without a history of international travel.
    • Ask patients with suspected or confirmed cyclosporiasis about their recent food and travel history to assist public health investigations.

  2. Test

    • Specifically request Cyclospora laboratory testing on stool specimens because routine ova and parasite (O&P) examinations might not reliably detect the parasite.
    • Consider molecular (PCR-based) diagnostic testing where available, because it can improve detection.
    • Diagnosis may be difficult as testing may not be positive based on results from a single specimen; several specimens collected on different days may be needed for diagnosis.

  3. Manage

    Treat confirmed cases of cyclosporiasis with 7–10 days of trimethoprim-sulfamethoxazole (TMP-SMX) for immunocompetent adults and children over age 2 months; consider longer courses for patients with immunocompromising conditions. Consult current CDC clinical guidance for recommended dosing.

  4. Notify

    Report suspected domestically acquired cases of cyclosporiasis to Public Health within 3 business days at 206-296-4774.

  5. Counsel

    • Advise patients to stay well hydrated, especially if diarrhea is frequent or severe.
    • While the life cycle of Cyclospora makes person-to-person spread unlikely, patients should avoid preparing food for others while they are sick to prevent spread of other foodborne gastrointestinal illness.
    • Cooking food to an internal temperature of158 degrees Fahrenheit or higher is the best way to kill Cyclospora.

Background

Cyclosporiasis is a gastrointestinal illness caused by the microscopic parasite Cyclospora. People can become infected by consuming food or water contaminated with the parasite. This illness is not usually spread person to person. Case counts typically rise during spring and summer months, and CDC considers May 1–August 31 the annual cyclosporiasis season. Previous outbreaks have been linked to consuming contaminated fresh produce.

Symptoms of cyclosporiasis typically begin about 1 week after exposure. Onset of symptoms can occur 2-14 days after being exposed. The most common symptoms include watery diarrhea, which can be frequent, along with loss of appetite, weight loss, bloating, nausea, and fatigue. Less common symptoms include low-grade fever and vomiting. Without treatment, symptoms can follow a remitting-relapsing course that can last from a few days to a month or longer. Illness can be severe but is not usually life-threatening. Complications can include malabsorption, cholecystitis, and reactive arthritis.

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