This difference may be related to HLA alleles since previous studies had demonstrated a protective effect of MHC class I-restricted CD8+ T cells (HLA-A*02 and HLA-CW*8), controlling the HTLV-I PVL and thus influencing the susceptibility to HAM/TSP [40,45–47], besides the HLA was not investigated among our cohort. Here, HLA-A is linked to tropical spastic paraparesis.