Prevalence, risk factors and risk perception of tuberculosis infection among medical students and healthcare workers in Johannesburg, South Africa.

BACKGROUND Tuberculin skin test (TST) and interferon gamma release assays (IGRAs) are both recommended for routine screening of healthcare workers (HCWs) in low tuberculosis (TB)-burden countries. More recently, based on scarce data, the World Health Organization strongly recommended that IGRA should not be used for occupational screening in high-burden settings. OBJECTIVE To assess the prevalence of latent tuberculosis infection (LTBI) determined among highly exposed HCWs and low-exposed medical students in Johannesburg, South Africa. Methods. We performed a cross-sectional study using both TSTs and IGRAs to determine the prevalence rate of LTBI in 79 medical students and 120 HCWs providing HIV and/or TB care. RESULTS The prevalence of LTBI among HCWs was 2- to 4-fold higher than that among medical students (56.7% v. 26.6% TST-positive; 69.2% v.15.2% IGRA-positive, respectively), with 3-fold higher odds for TST positivity and 12-fold higher odds for IGRA positivity among HCWs compared with students. Despite the perception of being at high risk, few HCWs protected themselves against LTBI. The majority of HCWs reported that they would participate in annual TST or IGRA screening. CONCLUSION Infection control strategies and occupational screening programmes for professional and lay HCWs, as well as medical students, should be implemented in all high-burden settings. Further research is needed to determine whether IGRA or TST is the optimal assay for periodical screening of HCWs in high-burden settings.