Characteristic distribution of HTLV type I and HTLV type II carriers amongnative ethnic groups in South America

To confirm the geographic and ethnic segregation of HTLV-I and HTLV-II carr iers in native populations in South America, we have conducted a seroepidem iological study of native populations in South America, including HTLV-I ca rriers distributed among seven ethnic groups in the Andes highlands of Colo mbia, Peru, Bolivia, Argentina, and Chile, and two ethnic groups on Chiloe Island and Easter Island; and HTLV-II carriers distributed among seven ethn ic groups of the lowlands along the Atlantic coast of Colombia, Orinoco, Am azon, and Patagonia, and one ethnic group on Chiloe Island, The incidence r ate of HTLV-I and HTLV-II carriers varied among the ethnic groups, ranging from 0.8 to 6.8% for HTLV-I seropositivity and from 1.4 to 57.9% for HTLV-I I seropositivity, A new HTLV-I focus was found among the Peruvian Aymara (1 .6%), the Bolivian Aymara (5.3%) and Quechua (4.5%), the Argentine Puna (2. 3%), and the Chilean Atacama (4.1%), while on HTLV-II focus was found among the Brazilian Kayapo (57.9%), the Paraguayan Chaco (16.4%), and the Chilea n Alacalf (34.8%) and Yahgan (9.1%). The distribution of HTLV-I/II foci sho wed a geographic clustering of HTLV-I foci in the Andes highlands and of HT LV-II foci in the lowlands of South America. It was thus suggested that Sou th American natives might be divided into two major ethnic groups by HTLV-I and HTLV-II carrier state.