Cryptosporidiosis

Cryptosporidiosis is an intestinal infection by Cryptosporidium parvum or C. hominis, acquired by faeco oral transmission from contaminated water, food, animals or person to person. Oocysts resist chlorine, so outbreaks follow contaminated water supplies and swimming pools.

• A leading cause of diarrhoea and mortality in young African children.
• In advanced HIV (CD4 under 100) infection is chronic, severe and wasting.

Incubation 3 to 7 days, then watery diarrhoea, cramps, nausea, vomiting, low grade fever and weight loss, lasting 1 to 2 weeks in the immunocompetent.

• In immunodeficiency: profuse watery diarrhoea of several litres daily, malabsorption, cholera like illness, biliary involvement (sclerosing cholangitis), pulmonary involvement.
• Differential diagnosis: giardiasis, cyclosporiasis, isosporiasis, microsporidiosis, cholera, rotavirus, bacterial gastroenteritis, CMV, Mycobacterium avium complex, HIV enteropathy.
• Complications: dehydration, malnutrition, electrolyte disturbance, wasting, biliary tract disease, respiratory infection, death in children and AIDS patients.

Stool examination for oocysts.

• Modified Ziehl Neelsen stain (pink red oocysts 4 to 6 micrometres), immunofluorescence, rapid antigen test, PCR; three stool samples on different days.
• Biopsy of the small bowel when stool tests are negative.
• HIV test and CD4, electrolytes, albumin, creatinine, full blood count.

Restore fluids and immunity; nitazoxanide shortens illness.

• Supportive: oral rehydration solution 200 to 400 mL after each loose stool in adults, IV Ringer lactate for severe dehydration, zinc 20 mg daily for 10 to 14 days in children, nutritional rehabilitation (energy 35 to 40 kcal/kg/day), hand washing, safe water (boiling), avoid swimming for 2 weeks after diarrhoea.
• Pharmacological: nitazoxanide 500 mg twice daily for 3 days in immunocompetent adults (1 to 3 years 100 mg twice daily; 4 to 11 years 200 mg twice daily; 12 years and over 500 mg twice daily); in HIV, nitazoxanide 500 to 1000 mg twice daily for 14 days, with paromomycin 500 mg four times daily for 14 to 21 days as an adjunct. Antiretroviral therapy (tenofovir, lamivudine and dolutegravir once daily) is the key measure, with CD4 recovery over 100 cells/mm3 leading to clearance. Loperamide 4 mg then 2 mg after each loose stool (maximum 16 mg daily) for symptoms once bloody diarrhoea is excluded.
• Procedures: endoscopic retrograde cholangiography with sphincterotomy for papillary stenosis; parenteral nutrition in intractable disease.
• Special groups: pregnancy, nitazoxanide after the first trimester and rehydration; children, nitazoxanide by age and zinc; HIV, rapid antiretroviral therapy; elderly, careful fluids.
• Red flags: severe dehydration, shock, weight loss over 10 percent, right upper quadrant pain with jaundice, CD4 under 50, diarrhoea persisting over 2 weeks.
• Follow-up: weekly weight and electrolytes; stool re-examination if symptoms persist; viral load at 3 months.