In particular, CXCL10 has been proposed as the most viable, prognostic biomarker for HAM/TSP, as the cerebrospinal fluid (CSF) levels of CXCL10 were well correlated with disease progression of HAM/TSP, better even than HTLV-1 PVL in PBMCs, i.e., the number of HTLV-1-infected cells [31, 32]. Here, CXCL10 is linked to tropical spastic paraparesis.