What protozoal infection is suspected in a patient with AIDS experiencing diarrhea?

In patients with AIDS, the immune system is significantly compromised, making them more susceptible to opportunistic infections. Among the protozoal infections, Cryptosporidiosis is particularly noted for its association with severe diarrhea in immunocompromised individuals.

Cryptosporidium is a protozoan parasite that can cause gastrointestinal illness, characterized primarily by profuse, watery diarrhea. In an individual with AIDS, the infection can lead to persistent diarrhea, dehydration, and weight loss. It is a common cause of diarrhea in patients with CD4 counts below 200 cells/mm3, which signifies advanced immunosuppression. The illness may be self-limiting in immunocompetent patients, but in those with AIDS, it can be severe and debilitating.

Additionally, the diagnostic approach often emphasizes the detection of Cryptosporidium oocysts in stool samples, and while other protozoal infections like Giardiasis and Amebiasis can also lead to diarrhea, Cryptosporidiosis is more specifically associated with advanced immunocompromised states, such as those seen in AIDS patients. Therefore, the detection of this protozoal infection is crucial in the management and treatment of diarrhea in these patients.