Community-based molecular epidemiology of HTLV type I in Taiwan and Kinmen: Implication of the origin of the cosmopolitan subtype in northeast Asia

To understand the possible origin and dissemination of HTLV-I infection in northeast Asia, community-based molecular epidemiological studies were cond ucted on the Kinmen Islands (off the coast of Fukien Province, China) and i n Taiwan, A total of 3831 Taiwanese from 3 townships (Pu-Li, Chu-Dung, and Pu-Tze) and 993 aborigines from 4 tribes in Taiwan participated in this stu dy. The prevalence rates of HTLV-I infection in adult residents from Pu-Li, Chu-Dung, and Pu-Tze were 0.82, 1.72, and 1.63%, respectively. None of the aborigines had HTLV-I infection. Previously, 0.73% of the adult population of Kin-Hu, Kinmen were found to have HTLV-I infection. Peripheral blood mo nonuclear cells were collected from HTLV-I carriers identified both in Taiw an and Kinmen and the HTLV-I LTR sequences were PCR amplified, subcloned, a nd sequenced for phylogenetic tree analysis. The results showed that all 6 HTLV-I isolates from Kinmen and 13 of 18 (72.2%) isolates from Taiwan were group a (transcontinental) of Cosmopolitan subtype, while 5 of 18 (27.8%) i solates from Taiwan were group b (Japanese) of Cosmopolitan subtype. Since all of the HTLV-I-infected persons were descendants of immigrants from main land China, the origin of the Cosmopolitan subtype in Taiwan and Kinmen may not have been Japan, as previously theorized, but China, possibly the resu lt of the migration of an infected population in the past several centuries .