Risk of tuberculous infection in an indigenous population from Amazonia, Brazil.
METHODS
Suruí Indians, Amazonia, Brazil.


OBJECTIVE
To estimate the prevalence and the annual risk of infection (ARI) of tuberculosis (TB) in an indigenous population in Brazil.


METHODS
We applied a method to estimate the prevalence of TB infection in populations with high bacille Calmette-Guérin (BCG) vaccine coverage. The method consisted of comparing levels of skin test reactivity in individuals tested with purified protein derivative (PPD) before and after stimulation with intradermal BCG. Fieldwork was carried out among the Suruí Indians (n = 993) in two phases, 3 months apart.


RESULTS
A total of 645 subjects were tested. In pre-BCG revaccination, tuberculin skin test (TST) indurations averaged 5.9 mm (33.5% > or =10 mm). In post-BCG revaccination TST, indurations averaged 9.4 mm (48.7% > or =10 mm). Conversion from non-reactor to reactor was 54.4%. The ARI ranged from 1.2% to 2.2%. In the logistic regression, age and history of TB were the strongest independent predictors of TB infection. BCG scar and the number of individuals per house were also associated with infection.


CONCLUSIONS
Tuberculous transmission is very high in the Suruí, surpassing the ARI reported for Brazil (0.6%). The epidemiology of TB in this indigenous population is related to unfavourable social and economic conditions, as well as to deficient health care services.
Basta
P C
PC
Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
Coimbra
C E A
CE
Camacho
L A B
LA
Santos
R V
RV
D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology / Q000208:ethnology; D005260:Female; D006801:Humans; D007199:Indians, South American; D008297:Male; D044382:Population Groups; D015995:Prevalence; D012306:Risk; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000208:ethnology* / Q000517:prevention & control; D014611:Vaccination
D001500:BCG Vaccine