The neuropathic pain profiling in retroviral infection Study: The NIPPR Study. This study contains pain related information reported by people living with Human T-lymphotropic cell virus (HTLV-1) infection. It includes those with and without neuropathic pain. NIPPR is a cross sectional deep profiling study examining sensory profiles and patient reported outcome measures. It also includes skin biopsy data. 22/40 participants have currently been recruited. It includes multiple measures including: • Patient reported pain outcome measures • Sites of pain • Psychophysical pain measures (quantitative sensory testing and conditioned pain modulation) • Intra-epidermal nerve fibre density • Patient reported measures of mood, sleep, quality of life and function.