Tuberculosis outbreak among high school students in Novi Pazar, Serbia 2016: a retrospective-cohort study

INTRODUCTION: Between February and November 2016, 17 tuberculosis (TB) cases were identified among high school students in Novi Pazar, Serbia. The objectives of our study were to describe the outbreak, to identify potential risk factors and to evaluate the applied control measures. METHODOLOGY: The outbreak was described by time, person and place. A retrospective cohort study was conducted. Attack rates, unadjusted relative risks (RR) and 95% confidence intervals (CI) were calculated. Multiple log-binomial regression analysis was performed to calculate adjusted RR. RESULTS: Sixteen of the total 17 cases occurred among grade 3 students, AR 5.5%. Previous TB family history, (RR = 5.29; 95% CI = 1.63-17.12), spending time with a known TB case at school (RR = 5.38; 95% CI = 1.48-19.55) and exposure to secondhand smoke (RR = 3.37; 95% CI = 1.11-10.29) were all significantly and independently associated with the occurrence of TB. CONCLUSIONS: Delayed diagnosis and reporting resulted in delayed initiation of the contact investigation and non-identification of latent TB cases probably favored the occurrence of this outbreak in a low incidence country. Public health authorities should consider revising the existing guidelines, promoting inter-sectorial collaboration and increasing awareness of public health professionals.