CXCL10 and tropical spastic paraparesis: Several candidate surrogate markers in the context of HAM/TSP have already been identified; these include Cerebrospinal fluid (CSF) markers (neopterin, C-X-C motif chemokine 10 (CXCL10), anti-HTLV-1 antibody titer, cell count, and total protein) and HTLV-1 proviral load (Matsuzaki et al., 2001; Olindo et al., 2005; Sato et al., 2013; Matsuura et al., 2016).