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-I) 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 of Papua 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-I were detected in 17 of 120 Hagahai, giving an HTLV-I seroprevalence of 14%, which is as high as that found in HTLV-I-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 of the high frequency of indeterminate HTLV-I Western immunoblots is unknown, but it is not unlike that encountered in other Melanesian populations. Whether this reflects incomplete specific reactivity to HTLV-I or the existence of HTLV-I-related retroviruses in Papua New Guinea is being investigated.