Prevalence and factors associated with latent tuberculosis infection in an indigenous population in the Brazilian Amazon.
BACKGROUND
Recent studies have shown a high incidence and prevalence of latent tuberculosis infection (LTBI) in indigenous populations around the World. We aimed to estimate the prevalence and annual risk of infection (ARI) as well as to identify factors associated with LTBI in an indigenous population from the Brazilian Amazon.


METHODS
We conducted a cross-sectional study in 2011. We performed tuberculin skin tests (TSTs), smears and cultures of sputum samples, and chest radiographs for individuals who reported cough for two or more weeks. Associations between LTBI (TST ≥5mm) and socio-demographic, clinical, and epidemiological characteristics were investigated using Poisson regression with robust variance. Prevalence ratio (PR) was used as the measure of association.


RESULTS
We examined 263 individuals. The prevalence of LTBI was 40.3%, and the ARI was 2.4%. Age ≥15 years [PR=5.5; 95% confidence interval (CI): 3.5-8.6], contact with tuberculosis (TB) patients (PR=3.8; 95% CI: 1.2-11.9), previous TB history (PR=1.4; 95% CI: 1.2-1.7), and presence of Bacillus Calmette-Guérin (BCG) scar (PR=1.9, 95% CI: 1.2-2.9) were associated with LTBI.


CONCLUSIONS
Although some adults may have been infected years prior, the high prevalence of infection and its strong association with age ≥15 years, history of TB, and recent contact with TB patients suggest that the TB transmission risk is high in the study area.
Programa de Pós-Graduação Stricto Sensu em Epidemiologia em Saúde Pública, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Jocieli
J
Malacarne
Programa de Pós-Graduação Stricto Sensu em Epidemiologia em Saúde Pública, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Diana Patricia Giraldo
DP
Rios
Departamento de Epidemiologia e Métodos Quantitativos em Saúde, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Cosme Marcelo Furtado Passos da
CM
Silva
Departamento de Epidemiologia e Métodos Quantitativos em Saúde, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
José Ueleres
JU
Braga
Departamento de Epidemiologia e Métodos Quantitativos em Saúde, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Luiz Antonio Bastos
LA
Camacho
Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
Paulo Cesar
PC
Basta
D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007199:Indians, South American / Q000706:statistics & numerical data*; D055985:Latent Tuberculosis / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D014374:Tuberculin Test