The medical records of 405 individuals interned in the LTCI who had been tested for HIV infection were requested for analysis of the following variables: [1] age and gender; [2] length of stay at LTCI (months); [3] causes and diagnoses on admission to LTCI according to International Classification of Diseases, 10th edition; [4] date of HIV diagnosis; [5] seropositivity for syphilis and hepatitis B and C viruses; [6] medications used at last prescription in medical file; and [7] mean CD4 lymphocyte count based on: total lymphocyte count/6 and total lymphocyte count x 0.8 x 0.2 or 0.3. The gene discussed is CD4; the disease is syphilis.