[Evolution of the prevalence of Mycobacterium tuberculosis infection in a penitentiary population on admission to prison from 1991 to 1996].

BACKGROUND

In Spanish prisons tuberculosis is a serious problem of public health. The analysis of temporal trends of tuberculous infection can show the effectiveness of interventions developed.

PATIENTS, MATERIAL AND

METHODS

All admissions in a prison between July 1991 and June 1996, without antecedents of chemotherapy or chemoprophylaxis, were included. We gathered sociodemographic variables as well as prison-related variables and HIV-risk factors. Tuberculin skin test was performed with 2 U of PPD RT-23 following the Spanish Consensus to Criterion of Tuberculous Infection. Statistic analysis was based on multivariate analysis (logistic regression).

RESULTS

37% of 1,459 prisoners analyzed were infected with M. tuberculosis. The tuberculous infection was more frequent among older prisoners (p < 0.001) and those with more time spent in prison (p < 0.001). Those with BCG-vaccination showed lesser levels of tuberculin reaction (p = 0.001). Temporal trends of tuberculous infection didn't show variations, but in intravenous drug users IVDU (p = 0.012) and those with time spent in prison (p = 0.08) it was increased.

CONCLUSIONS

We detected a high prevalence of tuberculous infection and the time spent in prison was one of the risk factors. The infection was probably underestimate among those with BCG-vaccination because of the criterion used. The tuberculous infection was increased among IVDU and those with antecedent of time spent in prison.