Cryptosporidiosis in AIDS — DTM&H MCQ

Correct answer: B — ART optimisation with supportive care

The correct answer is B, ART optimisation with supportive care. This man has cryptosporidiosis, confirmed by oocysts on modified acid-fast stool staining, occurring in the context of advanced HIV with a CD4 count of 42 cells/mm3. Cryptosporidium has no reliably curative specific antimicrobial, and disease severity and chronicity are driven directly by the degree of immunosuppression, so restoring immune function is the decisive intervention. UK guidance identifies early initiation or optimisation of combination antiretroviral therapy, alongside rehydration and nutritional supportive care, as the mainstay of managing this infection, with resolution following CD4 recovery. The stem's discriminators, chronic watery diarrhoea, profound CD4 depletion, and oocysts on acid-fast stain, all point away from bacterial or helminthic causes and towards an opportunistic protozoal infection whose control depends on immune reconstitution rather than antiparasitic monotherapy. Why the other options are wrong: C. Praziquantel: this is an anthelmintic used for schistosomiasis and other trematode or cestode infections, and has no activity against Cryptosporidium, which is a coccidian protozoan, not a helminth. A. Chloroquine: this is an antimalarial with no role in gastrointestinal protozoal disease; it does not target Cryptosporidium oocysts and would not address the underlying immunosuppression driving symptoms. E. Doxycycline: this is a broad spectrum antibacterial (and useful in some rickettsial or vibrio infections) but has no efficacy against Cryptosporidium, which is not a bacterium. D. Metronidazole monotherapy: metronidazole is effective against Giardia and Entamoeba histolytica but has no established activity against Cryptosporidium, and monotherapy without immune reconstitution would fail to control disease in someone with a CD4 count this low. Key point: In cryptosporidiosis complicating advanced HIV, immune reconstitution via ART, not a specific antiparasitic agent, is the definitive treatment that drives clinical and parasitological cure.

Reference: BHIVA, British HIV Association guidelines for the management of opportunistic infection in people living with HIV: gastrointestinal opportunistic infections (2020, updated), Section 6.4 Parasitic and helminth infections, https://bhiva.org/wp-content/uploads/2024/10/OI-guidelines-gastrointestinal.pdf