Cyclosporiasis Outbreak in the United States

The United States has reported a major outbreak of cyclosporiasis, a food- and water-borne intestinal illness.

What is Cyclosporiasis?

• Cyclosporiasis is an intestinal parasitic disease caused by the microscopic, single-celled protozoan parasite Cyclospora cayetanensis.
• It primarily infects the small intestine and is commonly associated with prolonged or recurring watery diarrhoea.
• It is generally not life-threatening but can become serious in children, older persons and immunocompromised individuals.

Causative Organism

• Pathogen: Cyclospora cayetanensis
• Type: Microscopic, unicellular coccidian protozoan parasite
• Affected organ: Small intestine

Mode of Transmission
The infection occurs when a person consumes:

• Food contaminated with infected human faecal matter.
• Contaminated drinking water.
• Raw or inadequately washed fresh fruits, vegetables, leafy greens or herbs.

Direct person-to-person transmission is unlikely because the parasite’s immature oocysts must remain in the environment for approximately one to two weeks before becoming infectious

Foods Commonly Associated with Outbreaks - Previous outbreaks have been linked to lettuce and other leafy vegetables, basil, parsley, cilantro, raspberries, snow peas and other raw or minimally processed fresh produce, while the present outbreak has been associated with shredded iceberg lettuce served at certain Taco Bell restaurants.

Diagnosis

• Diagnosed through stool examination; routine tests may miss the parasite.
• Multiple samples collected on different days may be required.
• Methods include special-stain microscopy, ultraviolet fluorescence microscopy and PCR testing.

Treatment

• Preferred drug: Trimethoprim-sulfamethoxazole (TMP-SMX) for 7–10 days.
• Longer treatment may be needed for immunocompromised patients.
• Fluids, electrolytes and rest help prevent dehydration.
• No vaccine is available; untreated illness may persist or relapse.

Public-Health Significance

• The outbreak highlights the vulnerability of modern food-supply chains, particularly those involving raw produce.
• The disease is frequently underdiagnosed and underreported because specialised laboratory testing is required.
• Effective control requires food traceability, surveillance, rapid outbreak reporting, safe irrigation water and strict sanitation throughout the farm-to-consumer supply chain.