Mycobacterium tuberculosis and human immunodeficiency virus co-infection in intravenous drug users on admission to prison

BACKGROUND: Intravenous drug users (IDUs) and prisoners are groups of great interest in human immunodeficiency virus (HIV) infection and tuberculosis (TB) epidemiology. AIM: To determine predictors and temporal trends of the co-infection of Mycobacterium tuberculosis and HIV in IDUs on admission to prison. PATIENTS AND METHODS: Between 1 January 1991 and 31 December 1997, 796 IDUs or former IDUs were studied. Socio-demographic and penitentiary variables were evaluated. HIV-positive patients with greater than or equal to 5 mm induration on tuberculin test were deemed co-infected. Analysis of factors associated with co-infection was based on a logistic regression model. RESULTS: Of the incoming prisoners, 44.0% were infected by M. tuberculosis, 43.8% by HIV and 20.1% were co-infected. Co-infection predictors were: 1) total prison time served previously (none, OR 1; <2 years, OR 2.44, 95%CI 1.28-4.64; greater than or equal to 2 years, OR 4.94, 95%CI 2.56-9.55); 2) age (16-25 years, OR 1; 25-29 years, OR 3.14, 95%CI 1.71-5.75; >29 years, OR 3.67, 95%CI 1.96-6.86); 3) tattoos (OR 1.56, 95%CI 0.98-2.49), 1) syringe sharing (OR 2.43, 95%CI 1.57-3.77) and 5) ex-IDU status (OR 1.87, 95%CI 1.23-2.82). No statistically significant variation in the annual co-infection tendency was observed (OR 1.10, 95%CI 0.98-1.22). CONCLUSIONS: The high prevalence of co-infection that was detected was associated with risk factors that could be amended by public health intervention.