This might be because the proportion of received ART in the neurosyphilis group was higher than that of the syphilis group, and standardized ART can help increase the level of CD4 cell count and not received ART increased the risk of neurosyphilis.[29] This result was similar to the study Salado et al[7] which indicated that patients with syphilis with a CD4 cell count <350 cells/μL, male, and not receiving ART were risk factors for developing neurosyphilis in patients with HIV infection. This evidence concerns the gene CD4 and HIV infectious disease.