Who Transmits Tuberculosis to Whom: A Cross-Sectional Analysis of a Cohort Study in Lima, Peru

Am J Respir Crit Care Med. 2024 Feb 28. doi: 10.1164/rccm.202307-1217OC. Online ahead of print.


Rationale: The persistent burden of TB disease emphasizes the need to identify individuals with TB for treatment and those at a high risk of incident TB for prevention. Targeting interventions towards those at high risk of developing and transmitting tuberculosis is a public health priority.

Objectives: We aimed to identify characteristics of individuals involved in tuberculosis transmission in a community setting, which may guide the prioritization of targeted interventions.

Methods: We collected clinical and socio-demographic data from a cohort of tuberculosis patients in Lima, Peru. We used whole-genome sequencing data to assess the genetic distance between all possible pairs of patients; we considered pairs to be the result of a direct transmission event if they differed by three or fewer SNPs and we assumed that the first diagnosed patient in a pair was the transmitter and the second to be the recipient. We used logistic regression to examine the association between host factors and the likelihood of direct tuberculosis transmission.

Main results: Analyzing data from 2,518 tuberculosis index patients, we identified 1,447 direct transmission pairs. Regardless of recipient attributes, individuals less than 34 years old, males, and those with a history of incarceration had a higher likelihood of being transmitters in direct transmission pairs. Direct transmission was more likely when both patients were drinkers or smokers.

Conclusions: This study identifies men, young adults, former prisoners, alcohol consumers, and smokers as priority groups for targeted interventions. Innovative strategies are needed to extend tuberculosis screening to social groups like young adults and prisoners with limited access to routine preventive care. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Keywords: interventions; pulmonary tuberculosis; transmission; whole-genome sequencing.