New admissions and asymptomatic TB cases seem to fuel TB epidemic in prisons, a cross sectional survey in Tanzania

There is an increased risk for tuberculosis (TB) infection and disease progression in prison settings. TB prevalence in prisons in low- and middle-income countries have been measured to be up to 50 -times higher than in the general population. The aim of the study was to perform active TB screening and estimate the burden of TB in central prisons in Tanzania mainland. We performed TB active case finding in five central prisons, Keko, Segerea, Ukonga, Butimba and Ruanda prison in Tanzania, using the Xpert on early morning or spot sputum sample from inmates and new entries between April 2014 and July 2015. A questionnaire that asked about the symptoms and risk factors for TB was administered before a sputum sample was collected. Out of 13,868 incarcerated individuals tested, 13,763 had valid results. TB prevalence among tested was 1550 per 100,000 population (214/13,763); new admissions contributed to the majority (61.68%) of TB cases, but prevalence was higher among inmates (1.75%) compared to new admissions (1.45%). Ukonga, an urban prison which incarcerates long-term convicted inmates had the highest prevalence of 4.02%. Male gender (OR = 2.51, p<0.001), repeated incarcerations (OR = 2.85, p<0.001), history of TB treatment (OR = 1.78, p = 0.002), TB symptoms (OR = 2.78, p = 0.006) and HIV infection (OR = 2.86, p = 0.002) were associated with positive TB results. New admissions could be the driving force of the TB epidemic in the penitentiary system. However, prison environments remain a major risk factor for developing active TB disease.