High Prevalence of and Risk Factors for Latent Tuberculosis Infection among Prisoners, Tianjin, China

The high incidence of tuberculosis (TB) among prisoners calls for interventions to identify latent tuberculosis infection (LTBI) before disease onset. To identify LTBI prevalence among prisoners and factors associated with it, we conducted a cross-sectional study in Tianjin. We randomly sampled 959 HIV-negative adult prisoners by ward clusters in 5 prisons and determined LTBI by seropositivity using an interferon-gamma release assay. The overall rate of LTBI was 52.0% (499/959) in the 5 facilities and ranged from 41.9% (72/172) to 60.9% (106/174). Age (adjusted odds ratio [aOR] 1.7, 95% CI 1.4-2.0 per 10 years), duration of imprisonment (aOR 1.2, 95 CI% 1.1-1.2 per year), previous incarceration (aOR 2.0, 95% CI 1.5-2.7), and facility-specific TB incidence (aOR 1.9, 95% CI 1.3-2.8) were risk factors for LTBI. These findings indicate possible TB transmission within prisons and suggest the necessity for early TB case detection, as well as prophylaxis.