Tuberculosis Contact clinical trials

Use TST and QFT-RD1 Test to Monitor the Tuberculous Infection in Patients, Close Contact People and Health Care Workers

Tuberculosis is still the most common infectious disease in Taiwan. The infants in Taiwan have been vaccinated at birth with BCG -Tokyo 171 strain since 1951. The BCG vaccination rate is 97% among first grade students in a recent national survey. Even with such a high BCG vaccination coverage, Taiwan still has a relatively high TB incidence rate. In 2004, there were totally 16,784 newly diagnosed TB cases and the annual incidence was 74.11 per 100,000 population nationally. Nearly 70% of the incidence cases were men and 30.4% were women. The mean age of incidence cases was 57.8 years old (median=63). 8,440(50.29%) patients were elderly than 65 years old. The elderly men did not receive the BCG vaccination and were the most important group to develop newly diagnosed tuberculosis and a special issue for the national TB control program in Taiwan. The tuberculin skin test (TST) is the only widely available method for detecting whether people have an immunologic reactivity to mycobacterial antigens and identified as latent tuberculosis infection (LTBI). Targeted tuberculin testing for latent TB infection is a very important strategy to identify subjects with high risk to develop tuberculosis including those who have recent infection with Mycobacterium tuberculosis or have clinical conditions that associated with an increased risk for progression of LTBI to active TB but the sensitivity was lower in elderly patients. Quantiferon-TB gold test (QFT-RD1) is a new diagnostic test for latent tuberculosis and a valuable alternative to skin testing. This whole-blood assay measures the production of IFN-  in whole blood upon stimulation by ESAT-6 and CFP-10 and allows distinction of latent M. tuberculosis infection from BCG-induced reactivity. ESAT-6 and CFP-10 are deleted from BCG Region 1 (RD1), not present in most nontuberculous mycobacteria and are highly specific indicators of M. tuberculosis infection. Thus, the aim of this study was to estimate the specificity and sensitivity of a whole blood IFN-γassay employing CFP-10 and ESAT-6, for the detection of M. tuberculosis infection in a clustered high risk elderly population. Changhwa Veterans Home is a government-expense veterans home with totally 519 residents in 2004.The inhabitants were all elderly people and lived in groups. , They did not receive BCG vaccination and were the high risk group to develop endemic TB infection. The annual TB incidence rate over there was 3,500 per 100,000 population.