Rezende GR, Lago BV, Puga MA, et al. - In view of high risk for hepatitis B virus (HBV) infection in prison population, researchers investigated the prevalence, incidence, HBV associated factors and the circulating genotypes/subtypes. This is the first cross-sectional multicenter study on this topic; recruitment of a total of 3,368 prisoners from 12 closed prisons was done. Further, a cohort study including 1,656 individuals after 12 months was done. HBV exposure (anti-HBc + ) was reported in 9.8%; 11.2% were female and 9.6% were male. HBsAg + was 0.6%. Susceptibility to HBV was reported in most individuals (60.2% female vs 52.2% male). Classification of HBV isolates as genotypes A (45.4%), D (27.3%) and F (27.3%) was done. Male exhibited association of HBV exposure with increased age. More evidence of HCV/HBV co-infection (10.7%) was observed in males vs females (3.4%); female prisoners had higher frequency of Treponema pallidum infection when compared with male prisoners (39.7% vs 19.1%). Results thereby suggest a high prevalence of HBV exposure in prisoners. Despite the low incidence of this infection, the occurrence of new cases emphasize the necessity to implement preventive measures.   .