The first published report demonstrated small changes in HIV-1 RNA levels and CD4 counts associated with syphilis infection; Buchacz et al. showed that among 52 HIV-1-infected men in California with primary or secondary syphilis, within-person changes in viral loads were slightly higher during versus prior to the syphilis infections (mean 0.22 log10 copies/mL, P = 0.02) that decreased after therapy (−0.10 log10 copies/mL, P = 0.52) [124]. This evidence concerns the gene CD4 and syphilis.