CD4 and infection: Thus, the level of CD4 cell count was no long considered a predictor for asymptomatic neurosyphilis in our analysis, though this was different from the previous reports.8,15,18 The reasons might include: first, the composition and size of our asymptomatic participants sample was different from those who have been reported; second, the repetitive infection of syphilis was produced by frequent high-risk behavior among asymptomatic patients.