In multivariate logistic regression analysis, the risk factors associated with occurrence of neurosyphilis were heterosexual contact as possible HIV transmission route (odds ratio [OR] 8.171; 95% confidence interval [CI]: 1.363–48.974), CD4 cell count <200 cells/μL (OR 1.486; 95% CI: 1.012–6.651), previous untreated with syphilis (OR 2.853; 95% CI: 1.114–6.249), and serum TRUST titer ≥1:16 (OR 5.580; 95% CI: 1.492–20.235). This evidence concerns the gene CD4 and syphilis.