Investigation of an outbreak of tuberculosis in one college in Xi'an

Objective To analyze an outbreak of tuberculosis (TB) in one college in Xi'an.Methods Information on the outbreak of TB in this college during October 2016 were collected.Epidemiological investigation was carried out to explore associated factors with the outbreak.Results About 2.91% of total students (17) were found infected with TB,among them 82.35% were detected through screening of close contacts with patients with no clinical symptoms.Ten of them (28.7%) came from the same class with positive rate of PPD test of 77.14%.The risk of TB infection in this class was 31.43 times higher than other classes.Five cases were found from the same dormitory of the first case,with the incidence rate of 83.33%.There are significant clustering characteristics in TB outbreak.Conclusion Close contacts with patients and no timely PPD test are the main reason for the outbreak in this college.PPD test should be strengthened and emphasized in the epidemic control of TB outbreak.