The Application And The Diagnostic Value Of Interleron Gamma Release Assay(IGRAs) For Tuberculosis Patients And High-risk Groups

Tuberculosis( TB) is a chronic infectious disease caused by Mycobacterium tuberculosis( MTB).According to report, there are 2 billions people which has been infected by MTB.The 8 millions of active pulmonary tuberculosis,the rest are latent tuberculosis infenction(LTBI). There has been a rising trend of TB epidemic in recent years, and rapid diagnosis of active TB and LTBI in the early stage is the key of TB prevention and control. There have been many weaknesses in TB diagnosis method in China over the past decades. MTB positive is the gold standard for TB diagnosis, but it is time-consuming and has a low sensitivity; there are sampling difficulties for sputum acid fast stain test, which shows a lower positive rate and is unable to differentiate from non MTB; the tuberculin skin test is used widely but it has a lower level of specificity. Interferon-gamma release assays diagnose tuberculosis infection by testing the number of specific T cells in region of difference 1 of MTB genome which secrete interferon-gamma when stimulated by early secreting antigenic target-6 and culture filtrate protein-10. It is not affected by the immune state and BCG vaccination, and has a high level of sensitivity and specificity. But its value of clinic application is quite controversial currently at home and abroad, which needs more clinical samples to validate.Objective:To observation of the positive cases and investigate the application value and the diagnostic value of IGRAs for pulmonary tuberculosis patients、high-risk groups and healthy people in China, where MTB infection rate and BCG vaccination rate is high while the income level is rather low.Method:Collect 255 cases as objects of study, who came to Hebei Chest Hospital between December 2013 and May 2014, including TB patients over 16 who practiced IGRAs, doctors and nurses from Internal Medicine Department of Hebei Chest Hospital, and people who came to take health checkups. According to their the contact condition of zctive tuberculosis patients,clinical manifestation, imaging examinations, TST, TB-DOT, TB-check, TB-Ab, specimen smear acid fast staining, MTB culture, histopathological examination, response to therapy, categorize them into TB group(Group A) with 85 cases; High-risk groups(Group B) with 85 cases; Group C with 85 healthy cases. To evaluate the application value and the diagnostic value of IGRAs for pulmonary tuberculosis patients、high-risk groups and healthy people by comparing the positive rates of different groups.Result:The positive rate applying IGRAs are 88.2%(75/85) in Group A; 45.9%(39/85) in Group B; 4.7%(4/85) in Group C. There is significant difference between A and B, A and C, B and C(P<0.05).Conclusion:① IGRAs’ diagnostic value is very high as far as active TB and LTBI is concerned. ② Close contact with infectious TB patients have a higher possibility of infecting MTB and becoming LTBI than those who have not.