An open-label, non-randomised, uncontrolled, proof-of-concept study of eight patients with 'definite' HTLV-I-associated myelopathy/Tropical Spastic Paraparesis (HAM/TSP). Eligible patients will have either early disease (of less than 2 years duration) or progressive disease (with observed clinical deterioration during the preceding 3 months.||Following 2 baseline assessments including Magnetic Resonance Imaging (MRI) of the spinal cord and a lumbar puncture for examination of the fluid around the brain (CSF) participants will be treated with a total of 7 infusions of the anti-TNF-alpha antibody infliximab over a period of 48 weeks. After the last on therapy assessment at 48 weeks participants will be followed up for a further 24 weeks. Study assessments will be clinical, virological, immunological and radiological. MRIs of the spinal cord will be obtained at weeks 12 and 72. CSF will be examined, on therapy, at week 12.