ENDEMIC INFECTION WITH HUMAN T-CELL LEUKEMIA LYMPHOMA VIRUS TYPE IIB IN ARGENTINEAN AND PARAGUAYAN INDIANS - EPIDEMIOLOGY AND MOLECULAR CHARACTERIZATION/

Human T cell leukemia/lymphoma virus (HTLV-II) type II infection was d etected by polymerase chain reaction or serologic analyses (or both) i n 22% of 697 Indians of six different ethnic backgrounds inhabiting th e Argentinean and Paraguayan Gran Chaco, None was infected with HTLVI. The prevalence of HTLV-II increased with age (14% in those <13 years and 23% in those greater than or equal to 13 years). HTLV-II infection was found in all 20 Gran Chaco communities studied, but marked differ ences (44%-4%) in the rate of infection were observed even in communit ies separated by only a few miles, These variations correlated closely with ethnicity, In the high-incidence communities, infection clustere d within families, with evidence for both sexual and perinatal transmi ssion, primarily via breast-feeding. By contrast, only 2% of 94 Mapuch e Indians from southern Argentina were positive for HTLV-II. Analyses of pol and long terminal repeat sequences from 15 Gran Chaco HTLV-II s trains indicated that they constitute a highly conserved branch of the HTLV-IIB substrain.