Introduction. According to World Health Organization about one-third of the world’s population is latently infected with tuberculosis. People infected with Mycobacterium tuberculosis have a risk of active disease of around 5-15% during their whole life. Recognizing infection before TB disease development enables prophylaxis against its activation. The tuberculin skin test is commonly used to diagnose latent tuberculosis infection, unfortunately, the sensitivity and specificity of the test are not satisfactory in Bacillus Calmette-Guerin vaccinated population. Interferon gamma release assay (IGRA) could be used instead.
Material and methods. 2487 samples of 2118 individuals were tested using QuantiFERON-TB Gold In-Tube 3 assay. The main population tested were patients before the start of biologic therapy for autoimmune arthritis.
Results. Twenty-one per cent of individuals tested were found to be positive in QuantiFERON-TB assay. 34 persons showed indeterminate result (7 because of high negative control, and 27 because of low mitogen control). The prevalence of positive results increased with age: 16.53% of children were found to be positive, compared with 25.35% of adults (especially older ones, 38.1% in the >60 years age group).
Conclusion. Interferon gamma release assay could be successfully used for the diagnostics of latent tuberculosis and shows a positive correlation with age.
