“The purpose of this presentation was to share the Japanese experiences with IGRA. Based on a 2002 clinical P5091 clinical trial trial of QuantiFERON(R)-TB Gold (stimulants: ESAT-6, CEP-10), a cut-off of 0.35 IU/ml was fixed, and 0.1 to 0.35 IU/ml is the ‘gray’ zone. Japan had a universal BCG vaccination and re-vaccination policy until 2006. As a consequence, the TST has very poor specificity in Japan and many low-risk people test positive to TST. The TST policy in Japan is to measure erythema rather than induration. Contact investigations
in adults are largely limited to case finding with chest X-ray screening. In Japan, contacts who are <30 years of age undergo TST. Those contacts that show an erythema diameter >30 mm are indicated for chemoprophylaxis. There is very poor evidence of diagnostic utility for TST in Japan. Four contact studies in Japan have shown the value of the QFT vs. TST, and there is an overall emerging large body of evidence showing that QFT performs better than TST. With the OFT test, BCG vaccination is no longer an issue, and targeting INH prophylaxis is now possible based on the positive QFT results. Also, the use of QFT results in significant savings in contact screening. In the Japanese experience, overall
QFT responses did significantly decline after the treatment of LTBI, despite the rate of reversion in QFT being low. And most of them stay Sapanisertib mouse positive for a long time even after 18 months of treatment. These results suggest that TB control needs more effective ways to treat LTBI. New
drugs (perhaps RMP for 3 or 4 months) or better regimens (i.e., 9 or 12 months of INH instead of 6 months) would have a large impact on TB control. Low QFT reversion rates do suggest that QFT would not be useful as a marker to evaluate the success of treatment for LTBI if the success of chemotherapy is defined as reversion in the QFT test. However, the finding that OFT responses significantly decline after the treatment of LTBI suggests the possibility that this decline could be used as a marker of the susceptibility of the infective M. tuberculosis strain to the prophylactic drug used.”
“Students in a primary school exposed to PD173074 clinical trial a tuberculosis (TB) patient (a teacher) were investigated using the TST, chest X-ray, and sequential QFT-G tests. The rate of QFT-G positivity in close contacts was 9.8% (4/41) and in casual contacts it was 1.8% (5/272; P = 0.020). The rate of TST positivity at the 5 mm cut-off for close contacts was 52.6% (20/38), and for casual contacts it was 67.2% (180/268; P = 0.078). The rate of TST positivity at the 10 mm cut-off for close contacts was 34.2% (13/38) and for casual contacts it was 28.7% (77/268; P = 0.488). Data suggest that QFT-G has the same performance characteristics in BCG-vaccinated children as it does in adults.