Table 3 shows the sensitivity and specificity of the different thresholds. Almost 95% of the OIs investigated occurred in patients with <350 CD4/mm3. Fifteen OIs were diagnosed in patients with ≥350 CD4 cells/mm3: 10 TB, 4 histoplasmosis, and 1 cryptococcal disease. Eighty-one (63.3%) of 128 patients with disseminated histoplasmosis had a CD4 cell count available. If histoplasmosis screening had been limited to patients with CD4 cell counts < 100 or <200 CD4 cells/mm3, 16 (19.7%) and 6 (7.4%) cases would have been missed, respectively. The gene discussed is CD4; the disease is tuberculosis.