What is the most common cause of chronic diarrhea in AIDS patients?

Chronic diarrhea in AIDS patients is frequently caused by opportunistic infections due to the immunocompromised state of these individuals. Cryptosporidium is a protozoan parasite that often causes significant gastrointestinal illness, particularly in patients with HIV/AIDS who have a low CD4 cell count. This organism can lead to persistent diarrhea that can be severe and debilitating, contributing to weight loss and malnutrition in affected patients.

While Isospora belli and Giardia lamblia can also cause diarrhea, they are less prevalent compared to Cryptosporidium in the context of AIDS. Salmonella, while it can lead to gastroenteritis, does not have the same association with chronic diarrhea in the AIDS population as Cryptosporidium, which is well-documented as a leading cause. Thus, Cryptosporidium stands out as the most common cause of chronic diarrhea in individuals with AIDS, particularly due to its prevalence and the severity of the illness it causes in immunocompromised patients.