Associated factors with prevalence and annual risk infection of tuberculosis among indigenous population from Brazilian Amazon
Recent studies had shown high incidence and prevalence of infection by Mycobacterium tuberculosis(MTB) and the emergence of drug resistance in indigenous populations around the world. However, little is known about the factors that contribute to maintenance of the disease in communities. Objective: To estimate the prevalence and annual risk of infection (ARI) by MTB and identify factors associated with transmission of the disease among the Wari'/Pakaanóva indigenous population from Brazilian Amazon.
METHODS:
We conducted a cross-sectional study in the Indigenous Land (IL) Igarapé Ribeirão, in February 2011. During house visits we applied Tuberculin test (TT) in the resident population. Moreover we offered smear and culture of sputum and chest X-ray to people who reported respiratory symptoms (RS). We conducted analysis of socio-demographic, and clinical-epidemiological characteristics the population and RS, respectively. We used Poisson regression with robust variance to assess the factors associated with TT ≥ 5mm. Prevalence ratio (PR) was used as association parameter.
RESULTS:
We examined 263 Indians, of whom 9.1% reported RS and 18.6% previous history of TB. The prevalence of MTB infection was 40.3 % and ARI 2.4%. The variables age ≥15 years old (PR=5.5, 95%CI:3.5-8.6), contact with TB patient (PR=3.8, 95%CI:1.2-11.9), previous TB (PR=1.4, 95%CI:1.2-1.7) and BCG scar (PR=1.9 , 95% CI:1.2-2.9 ) were associated with TT ≥ 5 mm.
CONCLUSIONS:
The prevalence of infection and ARI summarize the factors which influence the transmission dynamics of TB, in a specific area, and its trend reflects the impact of control measures employed. In comparative analysis, it was found that in a decade, there were virtually no changes in these indicators. Moreover, previous TB and the recent contact with TB patients reported indicate that control measures have no had positive impacts on control disease, revealing that IL Igarapé Ribeirão constitutes an area of high risk of transmission.