A first insight into tuberculosis transmission at the border of Ecuador and Colombia: a retrospective study of the population structure of Mycobacterium tuberculosis in Esmeraldas province

Abstract

ObjectiveTuberculosis (TB) is a major public health concern in Ecuador and Colombia, considering that both countries are high-burden TB settings. Molecular epidemiology is crucial to understand the transmission dynamics of Mycobacterium tuberculosis complex (MTBC) and to identify active transmission clusters of regional importance.MethodsWe studied the potential transmission of TB between Colombia and Ecuador through the analysis of the population structure of MTBC lineages circulating in the Ecuadorian province of Esmeraldas at the border with Colombia. A total of 105 MTBC strains were characterized by 24-loci MIRU-VNTR and spoligotyping.ResultsMTBC lineage 4 is only present in Esmeraldas; no MTBC strains belonging to Lineage 2–sublineage Beijing were found despite its presence in other provinces of Ecuador and, in Colombia. Genotyping results revealed a high degree of diversity for MTBC in Esmeraldas: Neither active transmission clusters within this province nor including MTBC strains from Colombia or other provinces of Ecuador were found.ConclusionOur data suggest that tuberculosis dynamics in this rural and isolated area may be not related to highly transmitted strains but could be influenced by other health determinants that favor TB relapse such as poverty and poor health system access. Further studies including a larger number of MTBC strains from Esmeraldas are necessary to test this hypothesis.

Prevalence, drug resistance, and genotypic diversity of the RDRio subfamily of Mycobacterium tuberculosis in Ecuador: a retrospective analysis for years 2012–2016

“…Although some biological advantages that improve virulence and transmissibility over other genotypes has been described for MTB RD Rio (36,44,45), this could explain its successful transmission in some countries like Venezuela, Brazil, Peru and Colombia, but not in Ecuador (22,46,47). In fact, two recent studies have shown a very limited transnational transmission of MTB between Ecuador, Colombia and Peru that would also explain the low prevalence of MTB RD Rio sublineage found in our study (48,49). The phylogenetic analysis of MTBC RD Rio strains identified in Ecuador suggests a regional cluster associated to provinces in the Coastal Region but with an elevated genetic diversity and lack of active transmission chains.…”