Cyclospora Infection

Cyclospora infection (cyclosporiasis) is an intestinal infection by the coccidian parasite Cyclospora cayetanensis, acquired by eating fresh produce (raspberries, basil, lettuce, coriander) or water contaminated with mature oocysts. Oocysts shed in stool need days to weeks to sporulate, so direct person to person spread does not occur.

• Seasonal in warm months; travellers' diarrhoea in endemic areas.
• Prolonged and relapsing disease in HIV.

Incubation about 1 week, then watery diarrhoea, anorexia, bloating, cramps, nausea, fatigue and weight loss; low grade fever.

• Relapsing, remitting course lasting weeks to months if untreated.
• Differential diagnosis: cryptosporidiosis, giardiasis, isosporiasis, microsporidiosis, bacterial enteritis, coeliac disease, tropical sprue, irritable bowel syndrome, HIV enteropathy.
• Complications: dehydration, malabsorption, weight loss, cholecystitis, Guillain Barre syndrome and reactive arthritis (rare), prolonged infection in immunosuppression.

Identify oocysts in stool.

• Modified acid fast stain (variable staining, oocysts 8 to 10 micrometres, twice the size of Cryptosporidium), UV autofluorescence (blue or green), PCR; examine multiple samples.
• Duodenal biopsy shows villous atrophy.
• HIV test and CD4, electrolytes, albumin.

Cotrimoxazole is the drug of choice.

• Supportive: oral rehydration, nutrition, hand washing, washing of produce thoroughly, safe water.
• Pharmacological: cotrimoxazole 960 mg (trimethoprim 160 mg with sulfamethoxazole 800 mg) twice daily for 7 to 10 days (children trimethoprim 5 mg/kg twice daily). In HIV: cotrimoxazole 960 mg four times daily for 10 days then 960 mg three times weekly (or daily) for secondary prophylaxis until CD4 is over 200 for 6 months. Sulfonamide allergy: ciprofloxacin 500 mg twice daily for 7 days (less effective), or nitazoxanide 500 mg twice daily for 7 days. Antiretroviral therapy with tenofovir, lamivudine and dolutegravir.
• Procedures: none.
• Special groups: pregnancy, cotrimoxazole with folic acid 5 mg daily in the first trimester, and discuss kernicterus risk near term; children, weight based dosing; HIV, long course and prophylaxis; sulfa allergy, desensitisation or ciprofloxacin.
• Red flags: severe dehydration, jaundice, persistent diarrhoea beyond 2 weeks of treatment, rash on cotrimoxazole, neurological weakness.
• Follow-up: review at 1 week; repeat stool at 2 weeks if symptoms persist; advise on food safety.