Associations of Mycobacterium tuberculosis genotypes with different ethnic and migratory populations in Taiwan.

The distribution of human Mycobacterium tuberculosis (MTB) genotypes is reportedly associated with geography, ethnicity and population migrations. Three groups of 208 patients with tuberculosis in Taiwan were sampled to test this observation: (1) 41 aborigines of Austronesian ethnicity, who have been inhabiting in Taiwan for more than 500 years; (2) 58 veterans of Han Chinese origin, who moved as the first generation from Mainland China to Taiwan 55-60 years ago; and (3) 109 patients representing the general Taiwanese population of Han Chinese whose ancestors migrated to Taiwan around 200-400 years ago. A total of 208 MTB isolates, one per patient, were analyzed by spoligotyping and mycobacterial interspersed repetitive unit (MIRU) typing. Beijing ancient strains and Haarlem strains predominated among aborigines, while Beijing modern strains were common among veterans and the general population. All Beijing strains were further analyzed by typing the NTF loci and RD deletion. Results suggest a chronological trend among Beijing isolates from the three groups: isolates from the aborigines had signatures compatible with ancient lineages, and those from veterans and the general population were more contemporary. Our data indicate that the distribution of MTB genotypes/strains in Taiwan is associated with different populations whose migratory activities occurred between 55 and 500 years ago. These results suggest that transmission of MTB may have been relatively restricted to close contacts.