TWENTY-5 YEARS OF HTLV TYPE-II FOLLOW-UP WITH A POSSIBLE CASE OF TROPICAL SPASTIC PARAPARESIS IN THE KAYAPO, A BRAZILIAN INDIAN TRIBE

A longitudinal study, spanning 25 years and great demographic and cult ural change, found a persistently high prevalence of human T-lymphotro pic virus type II (HTLV-II) in the Xikrin Kayapo Indians of Brazil, Mo re than 10% of the children continue to develop immune reactions to th e virus in infancy, a sharp increase in seroprevalence occurs between ages 15 and 30 years, and prevalence in older women still approaches 1 00%, This suggests that the major modes of transmission (breast milk a nd sexual activity) have not changed, The demonstration of stable main tenance of HTLV-II in one ethnic group makes migration theories of its dispersal more plausible, However, the infection may not be a negligi ble burden on population survival: at least 1 of 62 persons followed u ntil age 40 years died of possible tropical spastic paraparesis (TSP).