Investigation Of Latent Mycobacterium Tuberculosis Infection In Tuberculosis Professionals By Interferon Gamma Release Assay (igra)

Objective: To evaluate the screening value of latent mycobacterium tuberculosis infection by Interferon Gamma Release Assay (IGRA):in high BCG vaccination rate and incidence background. And investigated latent mycobacterium tuberculosis infection in TB professionals by IGRA.Methods: All subjects were divided into three groups: Group 1 included 128 TB professionals (60 physicians and 68 nurses). Group 2 included 60 family members in close contact with TB patients. Group 3 included 60 subjects without close contact with TB patients. T-SPOT.TB (Oxford Immunotec, Abingdon, UK) was used to assay the immune reactions of peripheral blood lymphocytes to two special secreted proteins of mycobacterium tuberculosis: 6-kDa early secreted antigenic target (ESAT-6) and culture filtrate protein 10 (CFP-10).Results: Positive rates in TB professionals, family members having and not having close contact with TB patients were 14.84% (19/128), 23.33% (14/60) and 5.00% (2/40), respectively. The positive rate of group 2 was significantly higher than that of group 3 (χ~2=6.002, P=0.023). The positive rate of group 1 was higher than that of group 2, although there was no significant difference but an increasing tendency. The positive rate of senior TB professionals having worked for at least 3 years was 27.12% (16/59), which was significantly higher than that (5.00%, 2/40) of group 3. Working duration≥3 years was confirmed as a risk factor for TB infection [RR= 6.24 (95%CI= 1.91 - 20.36)].Conclusions: In high BCG vaccination rate and incidence background, there are still higher sensitivity and specificity for detecting latent mycobacterium tuberculosis infection by Interferon Gamma Release Assay (IGRA) than tuberculin skin test (TST); TB professionals are at the high risk of latent mycobacterium tuberculosis infection and it has positive correlation with contact duration.