Tuberculosis enhanced transmission due to interterritorial mobility and prolonged diagnostic delay: a call for an integrated genomic analysis.

OBJECTIVES

Genomic epidemiology has revolutionized how we can delineate tuberculosis (TB) transmission. However, TB surveillance is restricted to the analysis of geographically limited populations, which impairs the identification of cross-regional transmission. This study aimed to integrate genomic data from independent populations, targeted strain sequencing, and refined epidemiological research to enhance the analysis of tuberculosis transmission.

DESIGN

Integration of sequencing data from Madrid and Almería, evolutionary analysis of the single-nucleotide polymorphisms (SNPs) identified in the cluster, standardized detailed interviews with patients to obtain more detailed epidemiological information and identify links among the individuals, and targeted sequencing of the strain marker SNPs to expedite the identification of new cases involved in the cluster.

RESULTS

We described the complex transmission patterns of a cluster involving 13 cases, characterized by the convergence of (i) interterritorial transmission due to the mobility of migrant cases, involving six different nationalities and autochthonous cases, (ii) enhanced transmission due to an undiagnosed advanced TB case, (iii) extensive exposures attributable to substantial social gatherings, and (iv) two independent populations where the majority of cases were exposed or diagnosed, respectively.

CONCLUSION

This study may serve as an illustration of the integrative efforts and simultaneous strategic, methodological, and analytical improvements that are required to address the numerous novel challenges arising in the proper surveillance of TB transmission in our current, increasingly complex epidemiological scenario.