Utility Of Interferon Gamma Release Assay And Tuberculin Skin Test For Screening Latent Tuberculosis Infection Among Health Care Workers A Comparative Study

Abstract

ABSTRACT INTRODUCTION: LTBI is characterized by a state of persistent immune response to Mycobacterium tuberculosis antigens without active TB manifestation. Despite being asymptomatic, individuals with LTBI serve as potential reservoirs for future TB outbreaks if left untreated. The seedbed for developing TB disease and continuous transmission could be latent tuberculosis infection. In healthy persons, the lifetime risk of reactivation of LTBI is 10%, with 5% acquiring active TB disease within the first 5 years following infection. Therefore, early identification and preventive treatment of LTBI among HCWs are crucial steps in TB control and infection prevention efforts AIM & OBJECTIVES OF THE STUDY: This study aimed to assess the distribution of latent tuberculosis infection (LTBI) and associated risk factors among healthcare workers (HCWs) using Tuberculin Skin Test (TST) and Interferon-Gamma Release Assay (IGRA) screening methods. MATERIAL AND METHODS: A structured questionnaire used for individual risk assessment of TB infection among HCWs like sociodemographic characteristics (e.g., age, gender, employed position and duration in that position), knowledge of TB prevention and control practices, History of diabetes mellitus, smoking, BCG vaccination, immunosuppression, current symptoms of tuberculosis, past history of Tuberculosis and treatment taken. History of tuberculosis, recent contact with new active tuberculosis case and have they undergone tuberculin skin test and when it was done. Following the completion of the risk assessment questionnaire, enrolled subjects underwent diagnostic tests to detect latent tuberculosis infection. RESULTS: A total of 73 HCWs participated, with a predominant age group of 20 to 29 years (56.2%). Females comprised 32.9% of the sample, while males constituted 67.1%. Lab technicians represented the majority (74.0%) among occupational roles.Results showed a comparable distribution between TB Skin Test and IGRA results, with 54.8% and 45.2% testing negative, and 50.7% and 49.3% testing negative, respectively. The TB Skin Test exhibited a sensitivity of 64.86%, specificity of 55.56%, PPV of 60.00%, NPV of 60.61%, and accuracy of 60.27%. The IGRA test showed a sensitivity of 55.56%, specificity of 64.86%, PPV of 60.61%, NPV of 60%, and accuracy of 60.27%. Disease prevalence among HCWs was estimated at 50.68%.Analysis of risk factors revealed significant associations with occupation and working hours (P < 0.0001). Lab technicians (38.9%) and attenders (71.4%) showed higher LTBI rates. Doctors and managers also displayed significant associations (P < 0.0001). There were no significant associations with age, gender, smoking history, or BCG immunization. CONCLUSION:In conclusion, this study provides valuable insights into LTBI distribution and risk factors among HCWs. It emphasizes the need for targeted preventive measures, regular screening, and infection control. Understanding occupational risks and working conditions is crucial for effective LTBI management. Further research with larger samples can enhance understanding and guide tailored interventions for LTBI prevention in healthcare settings.