Impact of Latent Infection Treatment in Indigenous Populations

Abstract

The aims of the present study were to identify risk factors associated with latent tuberculosis (TB), examine the development of active disease among contacts, and assess the effectiveness of treating latent infection in indigenous Brazilians from January 2006 to December 2011. This was a retrospective study consisting of 1,371 tuberculosis contacts, 392 of whom underwent treatment for latent infection. Morbidity-from-TB data were obtained from the Information System for Disease Notification (SINAN) database, and the contacts’ data were collected from the clinical records using forms employed by Special Department of Indigenous Health (SESAI) multidisciplinary teams, according to SESAI’s instructions. The variables that were associated with latent infection among the contacts were age (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.02–1.04) and close contact with a smear-positive index case (OR: 2.26, 95% CI: 1.59–3.22). The variables associated with the development of active TB among the contacts were a tuberculin skin test (TST) ≥10 mm (relative risk [RR]: 1.12, 95% CI: 1.07–1.17), age (RR: 1.01, 95% CI: 1.00–1.03), and treatment of latent infection (RR: 0.03, 95% CI: 0.01–0.27). The estimated number of latent infection treatments needed to prevent one case of active TB among the contacts was 51 treatments (95% CI: 33–182). In contacts with TST ≥10 mm, 10 (95% CI: 6–19) latent infection treatments were necessary to prevent one case of active TB. Age and close contact with a smear-positive index case were associated with latent TB. Screening with TST is a high priority among individuals contacting smear-positive index cases. Age and TST are associated with the development of active TB among contacts, and treatment of latent infection is an effective measure to control TB in indigenous communities.

Genetic Clustering of Tuberculosis in an Indigenous Community of Brazil

“…14,15 A previous study conducted in the nearby municipalities of Dourados and Amambai showed the expansion of treatment of latent TB infection in this population had a strong protective effect (relative risk: 0.03, 95% CI: 0.01-0.27). 16 These data may explain the low degree of genetic clustering in the household in this area. Most of the patients who were in genotypic clusters were diagnosed outside of the household and were not identified as a contact and within 2 years of another case in their cluster, which underscores the importance of contact investigations and prophylaxis.…”

Prevalence and factors associated with latent tuberculosis infection in an indigenous population in the Brazilian Amazon

“…The high risk of disease and transmission reported in Igarapé Ribeirão might be representative of other indigenous territories. Therefore, we conclude that within indigenous territories, there is need to apply more stringent control measures, including increased active searches for respiratory symptoms and use of chemoprophylaxis, which has effectively prevented TB in the indigenous GuaraniKaiowá people from the Midwest region of Brazil (36) , as well as further rigorously supervised treatment.…”

Prevalence and evolution of Mycobacterium tuberculosis infection in tuberculosis case contacts

“…A study that assessed the impact of LTBI treatment in an indigenous Brazilian population found that 13% of contacts became sick within 30 days after the diagnosis of the index case, 34.8% between 30 and 180 days and 52.2% after 180 days. These fi ndings highlighted the necessity of this option of TB control when established early (24) .…”