Human T Lymphotropic Virus Type I Infection in Papua New Guinea: High Prevalence among the Hagahai Confirmed by Western Analysis

A serologic survey for human T lymphotropic virus type I (HTLV-1) infection was conducted on nearly half of the entire 260-member Hagahai population, a hunter-horticulturist group occupying the northern banks of the Yuat River Gorge in Madang Province ofPapua New Guinea. For comparison, sera from two neighboring groups, the Pinai and Haruai, were tested . As determined by enzyme-linked immunosorbent assay (ELISA) and verified by Western immunoblot, IgG antibodies against HTLV-1 were detected in 17 of120 Hagahai, giving an HTLV-1 seroprevalence of 14%, which is as high as that found in HTLV-1-endemic regions such as southwestern Japan and the Caribbean basin . Infection tended to cluster in family groups and was more common with increasing age. The majority of ELISA positive (45/61) Hagahai sera were indeterminate, with 62% (28/45) exhibiting reactivity to three or more gag-encoded proteins . The clinical significance ofthe high frequency of indeterminate HTLV-1 Western immunoblots is unknown, but it is not unlike that encountered in other Melanesian populations. Whether this reflects incomplete specific reactivity to HTLV1 or the existence of HTLV-1-related retroviruses in Papua New Guinea is being investigated.