Histology as a diagnostic tool for intestinal isosporiasis in immunocompromised patients

Isospora belli is an opportunistic protozoan causing wasting diarrhea especially in patients with an immunocompromised status. Diagnosis is usually established by demonstrating the oocyst of the organism on stool examination, which however can often be inconclusive. Serological tests for isosporiasis are currently not available. In such a scenario, biopsy often provides evidence for a confirmatory diagnosis. We describe two such cases, in which intestinal biopsy was the only diagnostic evidence of isosporiasis as the cause for chronic diarrhea.