When comparing the groups of patients who developed the opportunistic illnesses of interest we found that patients who developed PCP had the lowest nadir CD4+ T lymphocyte counts (median of 55 cells/mm3 [IQR: 12–146], with 46 % of the patients having less than 50 cells/mm3), followed closely by those who developed cerebral toxoplasmosis (median of 63 cells/mm3 [IQR: 20–160], with 47 % of the patients having less than 50 cells/mm3). This evidence concerns the gene CD4 and cerebral toxoplasmosis.