Human T lymphotropic virus type 1 subtype C melanesian genetic variants of the Vanuatu Archipelago and Solomon Islands share a common ancestor.

Background: Melanesia is endemic for human T lymphotropic virus type 1 (HTLV-1) subtype C. In 2005, we identified 4 infected women from Ambae Island, Vanuatu. Subsequently, 4247 Ni-Vanuatu originating from 18 islands were enrolled to define HTLV-1 epidemiological determinants and to characterize the viral strains molecularly.