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Study identifies resistance to drugs against tuberculosis among indigenous populations


08/03/2021

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A pioneering study used the genomic sequencing of samples of Mycobacterium tuberculosis to assess the resistance of indigenous peoples to anti-tuberculosis drugs. Published on Scientific Reports, a magazine of the Nature group, the research also revealed a high frequency of polymorphisms associated with resistance to the main drugs used in the treatment. The article, titled Identification of a predominant genotype of Mycobacterium tuberculosis in Brazilian indigenous population, boasts the participation of researchers Paulo Basta and Reinaldo Santos, of the National School of Public Health (Ensp/Fiocruz), part of the research group on tuberculosis among the Guarani and Kaiowá indigenous peoples of Mato Grosso do Sul, developed by the research group on Epidemiology and Control of Tuberculosis in Indigenous Areas, and financed Fiocruz’s Scientific Innovation Program. 

The research used Whole Sequence Genome – WGS in samples of Mycobacterium tuberculosis isolated from indigenous individuals who got sick with tuberculosis in Brazil in the past few years. The main results of the overall sequencing of 66 samples revealed a high frequency of polymorphisms associated with resistance to the main drugs used in the treatment, showing not only the emergence of a serious public health issue, as well as an impending threat to tuberculosis control strategies that are commonly used among vulnerable populations.

In addition, the genetic analysis of the strains suggests that strains of M. tuberculosis different from the patterns predominantly observed in the Americas today have been introduced. This situation is to be expected in isolated communities. “However, as the Guarani and Kaiowá populations live in small territories with high demographic densities, considered indigenous reserves and located near towns in the region that borders with Paraguay, our discoveries show the extreme level of marginalization and prejudice suffered by this indigenous group, as the “fingerprints” of the isolates of M. tuberculosis studies seem to be widely divergent from other investigations made in the country, in which high-resolution genomic methods were used”, state the researchers. 

The article is the result of a partnership established with a team of the Michigan State University (MSU), a North American institution of teaching and research. It also relied on the collaboration of the Special Indigenous Sanitary District (DSEI) and of the Central Public Health Laboratory (Lacen), both from the state of Mato Grosso do Sul, in addition to the support of the Adolfo Lutz Institute (IAL) of São Paulo and Fiocruz researchers. The team of authors consists of Eunice Cunha (Lacen); Vera Simonsen and Lucilaine Ferrazoli (IAL), Syeda Hadi, Evan Brenner, Janani Ravi and Srinand Sreevatsan (MSU), Ida Viktoria Kolte, Daniel Antunes Villela, Reinaldo Souza-Santos and Paulo Basta (Fiocruz).

The stigma and prejudice associated with tuberculosis are expressed in different ways and contribute to the maintenance of disease transmission in the community; they are obstacles that delay early diagnosis and make it hard to administer proper treatment at the proper time. In order to minimize this impact, it is crucial to improve communication strategies and relations between population and health services, as well as to raise awareness among the surrounding society. The extension and the impact of the stigma and prejudice in the transmission and treatment of tuberculosis among the Guarani and Kaiowá populations can be better understood in another article by the study group, titled The contribution of stigma to the transmission and treatment of tuberculosis in a hyperendemic indigenous population in Brazil, recently published in Plos One.

In this second article, the team of authors consisted of Ida Viktoria Kolte, Islândia Maria Carvalho de Sousa and Paulo Basta (Fiocruz), in addition to Lucia Pereira and Aparecida Benites, indigenous researchers representing the Guarani and Kaiowá and resident in the indigenous villages under investigation. Their participation was crucial to make sure the interviews with those affected with the disease and their relatives had the necessary level of understanding and were conducted in their mother tongue, Guarani. This was the only way in which the team was able to define the categories of analysis used in the study and to have a real dimension of the burden and of the consequences of stigma, prejudice and discrimination in life and health conditions in the communities under study.

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