Considering only the 11 patients with CSF VDRL positive titers as having confirmed neurosyphilis, HIV viral load ≤ 400 copies/mm3 (OR = 0.16, 95 % CI 0.031‒0.83, p = 0.029) and CD4 count ≤ 350 cells/mm3 (OR = 10.0, 95 % CI 1.94‒51.21, p = 0.006) were independent risk factors to this outcome. This evidence concerns the gene CD4 and neurosyphilis.