TITLE:
Prevalence of Latent Tuberculosis (LTB) among Household Contacts of Newly Diagnosed Omani Pulmonary Tuberculosis Patients
AUTHORS:
Jeffrey Singh, Lamiya Balushi, Nada Mahrazi, Esklid Peterson, Olivier Koole, Fatma Al Ajmi, Padmamohan Kurup
KEYWORDS:
Latent TB Infection, Interferon Gamma Release Assay, Tuberculin Skin Test, Cavitary Lesions
JOURNAL NAME:
Journal of Tuberculosis Research,
Vol.8 No.1,
March
24,
2020
ABSTRACT:
Background: Oman is a high-income, low prevalent country for tuberculosis disease. Although the rates have remained static
over the last decade, the country is aiming for Tuberculosis (TB)
elimination. Household contacts of pulmonary TB (PTB) patients form a high-risk
group of susceptible individuals who could
remain reservoirs of active disease. Objective: A retrospective study was conducted to estimate the prevalence of latent
TB infection by Tuberculin Skin Test (TST)
or Interferon-Gamma Release Assay (IGRA) screening tests among the
household contacts of Omani patients with pulmonary tuberculosis. Design: A cross-sectional survey conducted between 2017 and 2018 of TB cases and
their contacts in Muscat Governorate, Oman. Results: Out of the 278 contacts identified, 188 contacts fulfilled the inclusion
criteria and were enrolled into the study.
The prevalence of Latent Tuberculosis Infection (LTBI) was 22.8% (95%
CI: 17.0 - 29.5) among household contacts. We found higher proportions of LTBI among
females than males (28.7% vs. 15%, p = 0.027). Those who were exposed to
Acid Fast Bacilli (AFB) smear positive cases were more likely to be LTBI (28.7%
versus 15% in smear negative cases; p = 0.047). We also found an increasing trend of infection (32.3%) in the oldest age
group (46 - 80 years). Conclusion: Besides children, female household contacts and older age contacts should
be prioritized for screening as they are more likely to be infected and develop
active disease.