Potential determinants of the changes in CD4+, CD8 + T-cell levels, and total lymphocyte level from T1 to T2, including age, nadir CD4 + T-cell level, CD4/CD8 ratio at T1, VDRL titre, and syphilis reinfection, were compared using non-parametric tests (Additional file [1]). Here, CD8A is linked to syphilis.