Prevalence of Latent Tuberculosis Infection Among Healthcare Workers Using Interferon-Gamma Release Assay

• SYED MAHMOOD-UL-HASSAN

  Assistant Professor of Medicine, Medical Unit 01, Services Hospital, Lahore

  Author

• MUHAMMAD IMRAN

  Consultant Physician, Medical Unit 2, Services Hospital, Lahore

  Author

Background: Healthcare workers (HCWs) are at increased risk of Mycobacterium tuberculosis infection due to occupational exposure. Latent tuberculosis infection (LTBI) poses a silent threat that can progress to active disease if undetected. Interferon-Gamma Release Assays (IGRAs) offer improved diagnostic accuracy over the traditional Tuberculin Skin Test (TST), particularly in BCG-vaccinated populations.

Objective: To determine the prevalence of LTBI among healthcare workers using the Interferon-Gamma Release Assay and to identify associated demographic and occupational risk factors.

Methods: A cross-sectional study was conducted from January 2024 to February 2025 at tertiary care centers across Punjab, Pakistan. One hundred HCWs, including doctors, nurses, laboratory technicians, and support staff, were enrolled. Demographic data and exposure history were recorded using a structured questionnaire. Blood samples were analyzed using the QuantiFERON-TB Gold Plus assay. Statistical analysis was performed using SPSS version 26.0, and associations were tested with Chi-square and Fisher’s exact tests (p < 0.05 considered significant).

Results: The overall prevalence of LTBI was 30%. Positivity was higher among nurses (37.0%) and laboratory staff (33.3%) compared to doctors (23.7%) and support staff (29.4%). Significant associations were observed between LTBI and employment duration ≥ 10 years (p = 0.02) as well as direct contact with TB patients (p = 0.01). Gender, age, and BCG vaccination status showed no significant relationships.

Conclusion: A substantial proportion of HCWs had latent tuberculosis infection, highlighting persistent occupational exposure risks. Regular IGRA-based screening, infection-control training, and use of personal protective equipment are essential to prevent transmission and reactivation of TB among healthcare staff.

1. Joshi R, Reingold AL, Menzies D, Pai M. Tuberculosis among health-care workers in low- and middle-income countries: a systematic review. PLoS Med. 2016;13(12):e1002150. doi:10.1371/journal.pmed.1002150

2. Zwerling A, Cojocariu M, McIntosh F, Pai M. Interferon-gamma release assays for tuberculosis screening of healthcare workers: a systematic review and meta-analysis. Thorax. 2018;73(9):867-875. doi:10.1136/thoraxjnl-2017-211193

3. Baussano I, Nunn P, Williams B, Pivetta E, Bugiani M, Scano F. Tuberculosis among healthcare workers: estimating the risk of infection. Occup Environ Med. 2017;74(7):501-507. doi:10.1136/oemed-2016-104133

4. Nasir N, Jabeen K, Raza A, Hussain SF. Prevalence and predictors of latent tuberculosis infection among healthcare workers in Pakistan. Int J Tuberc Lung Dis. 2019;23(4):474-480. doi:10.5588/ijtld.18.0564

5. Hedayati H, Khorvash F, Mahaki B, Maracy MR. Occupational exposure and prevalence of latent tuberculosis among hospital staff in Iran. J Infect Dev Ctries. 2020;14(6):589-595. doi:10.3855/jidc.12629

6. Uden L, Barber E, Ford N, Cooke GS. Risk of tuberculosis infection and disease among healthcare workers: an updated review. BMC Infect Dis. 2017;17(1):736. doi:10.1186/s12879-017-2851-9

7. Pai M, Behr MA, Dowdy D, Dheda K, Divangahi M, Boehme CC, et al. Tuberculosis. Nat Rev Dis Primers. 2016;2:16076. doi:10.1038/nrdp.2016.76

8. Lee SH, Kim YK, Cho YJ, Park JS, Lee SM, Lee CT. Long-term occupational exposure and risk of latent tuberculosis infection among healthcare workers. Int J Environ Res Public Health. 2021;18(8):4278. doi:10.3390/ijerph18084278

9. Diel R, Loddenkemper R, Nienhaus A. Evidence-based comparison of commercial interferon-γ release assays for detecting latent TB infection. Chest. 2018;153(4):1082-1092. doi:10.1016/j.chest.2017.12.010

10. Latorre I, Fernández-Ruiz M, Carrasco-Garrido P, Sanz-Ruiz T, Domínguez J. Interferon-gamma release assays for TB screening in BCG-vaccinated populations: usefulness and limitations. Expert Rev Anti Infect Ther. 2020;18(2):151-162. doi:10.1080/14787210.2020.1705054

11. O'Neal SE, Janssen S, Elwood K, Voss L, Romanowski K. Occupational tuberculosis among healthcare workers: current status and future directions. J Clin Tuberc Other Mycobact Dis. 2022;28:100333. doi:10.1016/j.jctube.2022.100333

12. World Health Organization. Global tuberculosis report 2023. Geneva: WHO; 2023. doi:10.4060/cc5684en

13. Yassin MA, Takele L, Gebresenbet S, et al. Prevalence of latent tuberculosis infection and associated risk factors among healthcare workers in Ethiopia. BMC Pulm Med. 2019;19(1):189. doi:10.1186/s12890-019-0964-5

14. Shin S, Park JS, Kim JY, et al. IGRA-based screening and risk factors for latent tuberculosis infection among nurses in Korea. BMC Pulm Med. 2021;21(1):198. doi:10.1186/s12890-021-01556-5

15. Ahmad AM, Rasheed M, Khan S, et al. Tuberculosis infection control practices and barriers in tertiary hospitals of Pakistan. J Pak Med Assoc. 2020;70(7):1170-1174. doi:10.5455/JPMA.30145

16. Chen B, Gu H, Liu H, et al. Implementation of interferon-γ release assay screening in healthcare settings: challenges and opportunities. Front Public Health. 2022;10:899112. doi:10.3389/fpubh.2022.899112

17. Seong GM, Kim JS, Kim MJ, et al. Comparison of tuberculin skin test and interferon-gamma release assay for detecting latent tuberculosis infection among healthcare workers. Clin Respir J. 2019;13(7):436-443. doi:10.1111/crj.13037

18. Saeed M, Al-Dossari K, Al-Sharif N, et al. Occupational risk and prevalence of latent TB infection among healthcare workers using IGRA in Saudi Arabia. PLoS One. 2020;15(11):e0241892. doi:10.1371/journal.pone.0241892

19. Jørstad MD, Dyrhol-Riise AM, Winje BA, et al. IGRA performance for screening healthcare workers in low-incidence countries: a 10-year follow-up study. Eur Respir J. 2021;57(6):2003182. doi:10.1183/13993003.03182-2020

20. Pan S, Wang F, Zhang Y, et al. Latent tuberculosis infection among healthcare workers: global burden and prevention strategies. Infect Drug Resist. 2024;17:1135-1148. doi:10.2147/IDR.S414562

• PDF

Copyright (c) 2025 SYED MAHMOOD-UL-HASSAN, MUHAMMAD IMRAN (Author)

This work is licensed under a Creative Commons Attribution 4.0 International License.