The decreased rate of cryptosporidiosis (50.1 vs 15.6 %) and isosporiasis (12.2 vs 2.2 %) among patients with a CD4 T cell count < 200 cells/μl may indicate the success of intervention efforts in reducing the significance of opportunistic intestinal parasitic infections in the specified high risk group. The gene discussed is CD4; the disease is cryptosporidiosis.