PATHOGENS

• HIV disease profoundly affects the gut and may manifest as diarrheal illness. HIV enteropathy is recognized by villous atrophy, crypt hyperplasia, and villous blunting and lymphocytes infiltration in the lamina propria.[14]
• HIV-associated alterations in mucosal immunity may predispose those with HIV to enteric bacterial infections.[7]
• Risk factors that contribute to HIV acquisition may increase risk of exposure to sexually transmitted infections that may manifest as enteritis or proctitis.[1]
• Advanced HIV/AIDS broadens the number of etiologic agents to include opportunistic infections that cause diarrhea.[13]
  • Acute: Salmonella, Shigella, Campylobacter, Clostridium difficile, E. coli (enteroaggregative EAEC), S. aureus, Vibrio parahemolyticus, Yersinia, norovirus[9] and other viruses (calicivirus, astrovirus, adenovirus).
  • Chronic: Cryptosporidium, microsporidia, MAC, CMV, Cyclospora, Giardia, Cystoisospora, Entamoeba histolytica, Strongyloides, HIV enteropathy, and the causes of acute diarrhea listed above, especially Salmonella.
  • CD4 < 50: Cryptosporidium,microsporidia, CMV, MAC.
  • Pathogen-negative, chronic, large-volume diarrhea: KS or lymphoma.
• Non-infectious causes: adverse drug reactions, inflammatory bowel disease, dietary (milk, sorbitol, caffeine), malabsorption, exocrine pancreatitic insufficiency, endocrine disease.