CHEST Guidelines-Response From Chest

Response From Chest

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The correspondence section of a 2015 issue of the CHEST journal includes a discussion surrounding a study that reported finding viable Mycobacterium tuberculosis (M. tuberculosis) in 10% of water samples and 1% of soil samples in metropolitan Tehran. Traditionally, M. tuberculosis is transmitted person-to-person through respiratory droplets, and humans are known reservoirs. The study challenges this by identifying potential environmental reservoirs.<br /><br />Dr. Eleanor S. Click addressed possible sources of cross-contamination, yet noted the study did not show matching genotypes between human and environmental isolates, which suggests contamination of water sources might not be due to random cross-contamination. The potential role of animals as reservoirs and vectors was also discussed, particularly the need for data on M. tuberculosis prevalence in animals in the Tehran region.<br /><br />The authors of the study, Velayati and colleagues, responded to this critique, affirming rigorous procedures to avoid laboratory contamination and supporting the reliability of their results. They noted the improbability of sewage contamination due to cultural practices and the types of water channels sampled, leaving open the possibility of contamination through expectoration. They also stressed the need for further inquiry into direct TB transmission via oral routes and the potential role of drinking contaminated water elsewhere.<br /><br />Ultimately, the correspondence highlights an evolving understanding of TB transmission routes. The authors suggest that if M. tuberculosis is found viable in environmental sources in more studies, it could have significant public health implications, urging reconsideration of possible transmission routes and the immune effects of exposure through environmental sources.

Keywords

Mycobacterium tuberculosis

environmental reservoirs

Tehran

cross-contamination

genotypes

animal vectors

oral transmission

public health

water contamination

CHEST journal