Two tales: Worldwide distribution of Central Asian (CAS) versus ancestral East-African Indian (EAI) lineages of Mycobacterium tuberculosis underlines a remarkable cleavage for phylogeographical, epidemiological and demographical characteristics

PLoS One. 2019 Jul 12;14(7):e0219706. doi: 10.1371/journal.pone.0219706. eCollection 2019.

Abstract

The East African Indian (EAI) and Central Asian (CAS) lineages of Mycobacterium tuberculosis complex (MTBC) mainly infect tuberculosis (TB) patients in the eastern hemisphere which contains many of the 22 high TB burden countries including China and India. We investigated if phylogeographical, epidemiological and demographical characteristics for these 2 lineages differed in SITVIT2 database. Genotyping results and associated data (age, sex, HIV serology, drug resistance) on EAI and CAS lineages (n = 10,974 strains) were extracted. Phylogenetic and Bayesian, and other statistical analyses were used to compare isolates. The male/female sex ratio was 907/433 (2.09) for the EAI group vs. 881/544 (1.62) for CAS (p-value<0.002). The proportion of younger patients aged 0-20 yrs. with CAS lineage was significantly higher than for EAI lineage (18.07% vs. 10.85%, p-value<0.0001). The proportion of multidrug resistant and extensively drug resistant TB among CAS group (30.63% and 1.03%, respectively) was significantly higher than in the EAI group (12.14% and 0.29%, respectively; p-value<0.0001). Lastly, the proportion of HIV+ patients was 20.34% among the EAI group vs. 3.46% in the CAS group (p-value<0.0001). This remarkable split observed between various parameters for these 2 lineages was further corroborated by their geographic distribution profile (EAI being predominantly found in Eastern-Coast of Africa, South-India and Southeast Asia, while CAS was predominantly found in Afghanistan, Pakistan, North India, Nepal, Middle-east, Libya, Sudan, Ethiopia, Kenya and Tanzania). Some geo-specificities were highlighted. This study demonstrated a remarkable cleavage for aforementioned characteristics of EAI and CAS lineages, showing a North-South divide along the tropic of cancer in Eastern hemisphere-mainly in Asia, and partly prolonged along the horn of Africa. Such studies would be helpful to better comprehend prevailing TB epidemic in context of its historical spread and evolutionary features, and provide clues to better treatment and patient-care in countries and regions concerned by these lineages.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Africa, Eastern / epidemiology
  • Aged
  • Asia / epidemiology
  • Bacterial Typing Techniques
  • Bayes Theorem
  • Child
  • Child, Preschool
  • DNA, Bacterial
  • Drug Resistance, Microbial
  • Extensively Drug-Resistant Tuberculosis / epidemiology*
  • Extensively Drug-Resistant Tuberculosis / microbiology*
  • Female
  • Genetic Variation
  • Genotype
  • Geography
  • Humans
  • India / epidemiology
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / genetics*
  • Phylogeny
  • Phylogeography*
  • Sex Factors
  • Young Adult

Substances

  • DNA, Bacterial

Grants and funding

DC was awarded a Ph.D. fellowship by the European Social Funds through the Regional Council of Guadeloupe, while the work done at Institut Pasteur de la Guadeloupe was supported by a FEDER grant, financed by the European Union and Guadeloupe Region (Programme Opérationnel FEDER-Guadeloupe-Conseil Régional 2014-2020, Grant number 2015-FED-192). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.