HIV-Associated Diarrhea

Diarrhoea in HIV is frequent, prolonged and often caused by opportunistic and conventional enteric pathogens, or by HIV enteropathy and antiretroviral drug effects. Acute is under 14 days, persistent 14 to 30 days and chronic over 30 days.

• Pathogens: Cryptosporidium, Cystoisospora belli, Cyclospora, microsporidia (Enterocytozoon bieneusi), Giardia, Entamoeba histolytica, Salmonella, Shigella, Campylobacter, Clostridioides difficile, cytomegalovirus, Mycobacterium avium complex, tuberculosis, Strongyloides.
• Risk increases with CD4 under 200, contaminated water, malnutrition and poor sanitation.

Watery, bloody or fatty diarrhoea with cramps, bloating, nausea, weight loss, dehydration and fever depending on the cause.

• Large volume watery diarrhoea with weight loss: Cryptosporidium, Cystoisospora, microsporidia; dysentery: Shigella, Entamoeba, CMV; fever and bacteraemia: non typhoidal Salmonella.
• Differential diagnosis: antiretroviral side effects (lopinavir ritonavir, nelfinavir), lactose intolerance, immune reconstitution, lymphoma, Kaposi sarcoma of gut, pancreatic insufficiency, cholera, medication effect.
• Complications: dehydration, electrolyte disturbance, malnutrition, malabsorption of antiretroviral drugs, bacteraemia, toxic megacolon, perforation, death.

Assess hydration first, then identify the cause.

• Stool microscopy for ova, cysts and parasites (three samples), modified Ziehl Neelsen or auramine stain for Cryptosporidium, Cystoisospora and Cyclospora, stool culture, Clostridioides difficile toxin or PCR, multiplex PCR where available.
• Blood cultures if febrile; full blood count, urea, electrolytes, albumin, CD4 count and viral load.
• Colonoscopy with biopsy for CMV, MAC and microsporidia in persistent disease.

Rehydrate, treat the cause and restore immunity.

• Supportive: oral rehydration solution 200 to 400 mL after every loose stool (adults) and 50 to 100 mL/kg over 4 hours in moderate dehydration; IV Ringer lactate 30 mL/kg over 30 minutes then 70 mL/kg over 2.5 hours for severe dehydration; zinc 20 mg daily for 10 to 14 days in children; continue feeding; correct potassium; lactose free diet.
• Pharmacological: bacterial dysentery: ciprofloxacin 500 mg twice daily for 3 to 5 days (ceftriaxone 2 g IV daily for severe); Cystoisospora: cotrimoxazole 960 mg twice daily for 10 days then 960 mg daily as secondary prophylaxis; Cryptosporidium: nitazoxanide 500 mg twice daily for 3 to 14 days and rapid antiretroviral therapy; microsporidia: albendazole 400 mg twice daily for 3 weeks; Giardia: metronidazole 500 mg three times daily for 5 to 7 days; amoebic colitis: metronidazole 750 mg three times daily for 7 to 10 days, then paromomycin 500 mg three times daily for 7 days; Clostridioides difficile: vancomycin 125 mg four times daily orally for 10 days; CMV colitis: ganciclovir 5 mg/kg IV every 12 hours for 14 to 21 days; MAC: clarithromycin 500 mg twice daily with ethambutol 15 mg/kg daily. Loperamide 4 mg then 2 mg after each loose stool (maximum 16 mg daily) for non bloody diarrhoea once infection is excluded. Antiretroviral therapy: tenofovir, lamivudine and dolutegravir once daily.
• Procedures: colonoscopy with biopsy; endoscopy; nasogastric feeding.
• Special groups: children, ORS and zinc, antimicrobials by weight; pregnancy, avoid ciprofloxacin and metronidazole in first trimester when possible, albendazole avoided in first trimester; elderly, caution with fluid load and loperamide; renal impairment, adjust doses.
• Red flags: severe dehydration, shock, bloody stool with fever, abdominal distension, perforation signs, altered consciousness, weight loss over 10 percent, CD4 under 100.
• Follow-up: review in 48 to 72 hours; weight and electrolytes; continue prophylaxis until CD4 over 200 for 6 months.