Map of distribution of HTLV/STLV viral isolates of known geographic origin. (Small rectangles) HTLV-I; (large rectangles) HTLV-I high endemicity; (triangles) STLV-I; (green ovals) HTLV-II endemic ethnic groups; (red ovals) HTLV-II IVDU; (star) STLV-II.