Latent TB infection diagnosis in population exposed to TB subjects in close and poor ventilated high TB endemic zone in India.

The present study was designed to investigate the utility of Quantiferon TB gold (QFT-G) and Tuberculin skin test (TST) for diagnosis of latent TB infection (LTBI) in high crowding TB endemic zone of Nagpur, India and their comparison with associated risk factors.Out of 342 eligible participants, QFT-G and TST were performed in 162 participants.The prevalence of LTBI observed according to QFT-G and TST was 48% and 42% respectively, with an agreement of 52.47%. QFT-G positivity was associated with age while TST positivity was associated with body mass index (BMI). Duration of exposure emerged as a key risk factor significantly associated with both the tests.The prevalence of LTBI was quite high in the studied zone as detected by both the evaluated tests and thus, the combination of both the tests will be best predictive for LTBI in such high TB endemic regions

Laboratory Investigations on the Diagnosis of Tuberculosis in the Malnourished Tribal Population of Melghat, India

<div><p>Background</p><p>Malnutrition is a major risk factor for the development of tuberculosis (TB). In India, Melghat is among the tribal regions which consist of highest number of malnutrition cases. Because of the paucity of TB data from these malnourished areas there is an urgent need for the development and evaluation of improved TB diagnostic tests. In the present study, three in house developed diagnostic tests namely TB-Ag(antigen) ELISA, Adenosine deaminase (ADA) estimation and IS<i>6110</i> polymerase chain reaction (PCR) assay were investigated for the detection of <i>Mycobacterium tuberculosis</i> (<i>M. tb.</i>) infection.</p> <p>Methods</p><p>For investigation, blood samples were collected from 128 study subjects from six villages of Melghat tribal area and evaluated using three in house developed assays, namely TB-Ag ELISA, ADA estimation and IS<i>6110</i> PCR.</p> <p>Results</p><p>The TB-Ag ELISA method yielded 83% sensitivity and 94% specificity. The ADA and PCR assay gave a sensitivity of 61% and 49% and specificity of 62% and 98% respectively. A considerable good agreement of 82.81% (k=0.472) between TB-Ag ELISA and PCR was observed. The overall sensitivity of TB-Ag ELISA was significantly higher (p<0.05) than the ADA and PCR while PCR yielded highest specificity among all the three evaluated tests.</p> <p>Conclusions</p><p>We concluded that the routine use of TB-Ag ELISA can be useful for screening of suspected TB patients in the malnourished population where sophisticated laboratory set up is difficult.</p> </div

Correlation between the QFT-G and TST assays in exposed population (<i>n</i> = 162).

<p>Correlation between the QFT-G and TST assays in exposed population (<i>n</i> = 162).</p

General characteristics of TB exposed cases (<i>n</i> = 162).

†<p>Out of 117.</p

Correlation between patient characteristics and QFT results obtained through bivariate and multivariable logistic regression analysis (<i>n</i> = 162).

<p>*<i>P</i><0.05;</p><p>**<i>P</i><0.0001;</p>‡<p>Bivariate analysis;</p>†<p>Parsimonious multivariate logistic regression model;</p>+<p><i>n</i> = 117 (45 unknown).</p

Multinomial univariate logistic regression to determine the correlation of risk factors with concordant and discordant test results.

<p>*<i>P</i><0.05;</p><p>**<i>P</i><0.0001;</p><p>QFT−/TST – as reference level.</p

QFT and TST assay in initial and Follow studies and their correlation with Baseline characteristics.

<p>NA - Not Available.</p><p>ND - Not Done.</p><p>*Conversion of QFT Test into positive after follow up.</p>#<p>QFT Test still remains positive after follow up.</p>$<p>QFT Test still remains negative after follow up.</p>¥<p>Conversion of TST Test into positive after follow up.</p>¶<p>TST Test still remains positive after follow up.</p>Φ<p>TST was not done in follow up cases.</p

Study flow diagram.

<p>Study flow diagram.</p