Population Genomics of Mycobacterium tuberculosis in Ethiopia Contradicts the Virgin Soil Hypothesis for Human Tuberculosis in Sub-Saharan Africa

TY - JOUR

T1 - Population Genomics of Mycobacterium tuberculosis in Ethiopia Contradicts the Virgin Soil Hypothesis for Human Tuberculosis in Sub-Saharan Africa

AU - Comas, Iñaki

AU - Hailu, Elena

AU - Kiros, Teklu

AU - Bekele, Shiferaw

AU - Mekonnen, Wondale

AU - Gumi, Balako

AU - Tschopp, Rea

AU - Ameni, Gobena

AU - Hewinson, R. Glyn

AU - Robertson, Brian D.

AU - Goig, Galo A.

AU - Stucki, David

AU - Gagneux, Sebastien

AU - Aseffa, Abraham

AU - Young, Douglas

AU - Berg, Stefan

PY - 2015/12/10

Y1 - 2015/12/10

N2 - Colonial medical reports claimed that tuberculosis (TB) was largely unknown in Africa prior to European contact, providing a "virgin soil" for spread of TB in highly susceptible populations previously unexposed to the disease [1, 2]. This is in direct contrast to recent phylogenetic models which support an African origin for TB [3-6]. To address this apparent contradiction, we performed a broad genomic sampling of Mycobacterium tuberculosis in Ethiopia. All members of the M. tuberculosis complex (MTBC) arose from clonal expansion of a single common ancestor [7] with a proposed origin in East Africa [3, 4, 8]. Consistent with this proposal, MTBC lineage 7 is almost exclusively found in that region [9-11]. Although a detailed medical history of Ethiopia supports the view that TB was rare until the 20th century [12], over the last century Ethiopia has become a high-burden TB country [13]. Our results provide further support for an African origin for TB, with some genotypes already present on the continent well before European contact. Phylogenetic analyses reveal a pattern of serial introductions of multiple genotypes into Ethiopia in association with human migration and trade. In place of a "virgin soil" fostering the spread of TB in a previously naive population, we propose that increased TB mortality in Africa was driven by the introduction of European strains of M. tuberculosis alongside expansion of selected indigenous strains having biological characteristics that carry a fitness benefit in the urbanized settings of post-colonial Africa.

AB - Colonial medical reports claimed that tuberculosis (TB) was largely unknown in Africa prior to European contact, providing a "virgin soil" for spread of TB in highly susceptible populations previously unexposed to the disease [1, 2]. This is in direct contrast to recent phylogenetic models which support an African origin for TB [3-6]. To address this apparent contradiction, we performed a broad genomic sampling of Mycobacterium tuberculosis in Ethiopia. All members of the M. tuberculosis complex (MTBC) arose from clonal expansion of a single common ancestor [7] with a proposed origin in East Africa [3, 4, 8]. Consistent with this proposal, MTBC lineage 7 is almost exclusively found in that region [9-11]. Although a detailed medical history of Ethiopia supports the view that TB was rare until the 20th century [12], over the last century Ethiopia has become a high-burden TB country [13]. Our results provide further support for an African origin for TB, with some genotypes already present on the continent well before European contact. Phylogenetic analyses reveal a pattern of serial introductions of multiple genotypes into Ethiopia in association with human migration and trade. In place of a "virgin soil" fostering the spread of TB in a previously naive population, we propose that increased TB mortality in Africa was driven by the introduction of European strains of M. tuberculosis alongside expansion of selected indigenous strains having biological characteristics that carry a fitness benefit in the urbanized settings of post-colonial Africa.

UR - http://www.scopus.com/inward/record.url?scp=84955675429&partnerID=8YFLogxK

UR - https://www.cell.com/cms/10.1016/j.cub.2015.10.061/attachment/8f7c7bb1-3f57-4dcd-bbc0-768c2ce5fb82/mmc1.pdf

U2 - 10.1016/j.cub.2015.10.061

DO - 10.1016/j.cub.2015.10.061

M3 - Article

C2 - 26687624

AN - SCOPUS:84955675429

VL - 25

SP - 3260

EP - 3266

JO - Current Biology

JF - Current Biology

SN - 0960-9822

IS - 24

ER -