Correlates of Mycobacterium tuberculosis infection in a prison population

Prisons represent a crucial setting for tuberculosis control. Currently, there is scarce information concerning Mycobacterium tuberculosis (MT) infection in European prisons, and no data are available for Italy. This study aims to describe the prevalence and correlates of MT infection in an Italian prison population. In this multicentre cross-sectional study, 1,247 inmates from nine prisons were recruited and asked to undergo questioning regarding socio-economic and demographic variables, tuberculin skin testing (TST), chest radiographs and testing for HIV, hepatitis B and hepatitis C virus infection. TST was positive in 17.9% of the 448 evaluable subjects. With multivariate logistic regression (performed among male inmates), MT infection was correlated with age (adjusted odds ratio (OR) 4.12 for inmates aged 31-40 yrs; 3.78 for those aged > 40 yrs), being foreign-born (OR=4.9), education <= 5 yrs (OR = 1.88) and length of detention (increased risk per yr: 11%). As with elsewhere in the world, the prison system in Italy features a population with an increased rate of Mycobacterium tuberculosis infection and at-risk rate for Mycobacterium tuberculosis transmission. Improved tuberculosis surveillance and control measures are deemed necessary in correctional facilities nationwide, especially for subjects with the above risk factors and those who are HIV infected, in whom the tuberculin skin testing can be misleading. The screening of entrants is particularly important to avoid undiagnosed smear-positive tuberculosis cases.