The epidemiology of myelopathy associated with human T-lymphotropic virus 1.

A progressive spastic myelopathy is one of the principal manifestations of the human T cell lymphotropic virus type 1. Recent research is reviewed on the geography and epidemiology of this specific form of tropical spastic paraparesis. First recognized in the Caribbean, Colombia and Japan, it is now also confirmed as a major neurological problem in areas of eastern Brazil, western equatorial Africa, Natal and Seychelles, with other scattered foci world-wide. Accurate surveys call for sophisticated techniques including polymerase chain reaction amplification. The only defined modes of spread are by breast feeding, sexual contact and blood cell infusion. The onset of neurological disease is associated with high antibody titres and a high rate of spontaneous T lymphocyte proliferation. Molecular analysis has revealed no nucleotide sequence variation in cases with or without myelopathy. In non-transfusion cases the clinical attack rate is low with a very long latent period, but there are unexplained regional differences and familial cases are an important exception. Current research is focused on possible local, ethnic, or genetic co-factors.