Prevalence and risk factors of latent tuberculosis among healthcare workers in Sana'a city, Yemen using whole blood interferon-? release assay

Abstract

Background and aims: Tuberculosis (TB) is a critical problem of public health. Diagnosis and screening of latent Mycobacterium tuberculosis infections (LTBI) are essential to control their spread. The goal of the study was to clarify the prevalence and risk factors for LTBI using IGRA among healthcare works (HCWs) in Sana'a city, Yemen.

Methods: The cross-sectional study was performed in three chosen tertiary hospitals in Sana'a city. Healthcare workers who participated in this survey were asked to complete a questionnaire and donate 5 ml of blood to perform the IGRA. A total of 180 healthcare workers were involved in this study; aged 20-60 years, 45.6% males and 54.4% females. Blood samples were collected and then tested by Interferon-gamma (IFN-γ) release assays that measure the presence of specific M. tuberculosis reactive T-cells sensitized by a previous infection with M. tuberculosis using the Quanti FERON-TB Gold In Tube assay (QFT-GIT). The data were evaluated for the positive association of interferon-gamma.

Results: The overall positivity rate IFN-γ of our healthcare workers was 20%, and for females it was 28.6%, with an associated odds ratio equal to 3.7, CI=1.5-8.7, P=0.001, while for males it was only 9.7%. Positive rates IFN-γ increased with increasing age, as a high IFN-γ positive rate occurred in the 50-60-year age group was 50%, with OR=5.5, CI=2.2-13.6, P < 0.001. There was a significant association between IFN-γ positive latent tuberculosis and unimmunized childhood BCG (OR=2.2, CI=1.03-4.7, P=0.03), diabetics (OR=4.2, CI=1.5-12, P=0.003), smoking (OR=2.7, CI=1.2-6.1, P=0.009) and contacting cases with active TB (OR=4.1, CI=1.4-12.2, P=0.007).

Conclusion: It was found that the rate of LTBI among HCWs is high in Sana'a, central Yemen. Factors at both the institutional and individual level can influence the prevalence of LTBI among HCWs. Since contact with active TB patients has been identified as a risk factor for LTBI, more effective TB infection control measures are necessary in health care facilities and congregate settings and to create awareness about TB risk factors in hospitals and as an occupational hazard.