| Tuberculosis is a public health problem throughout the world, causing great threats to human health. Tuberculosis is caused by Mycobacterium tuberculosis, transmitted by airborne. The tuberculosis cases are mainly located in developing countries. China is one of the top22countries with the highest tuberculosis burden. The majority of M. tuberculosis infected cases are latent tuberculosis infection (LTBI), of which about5-10%could shift to active tuberculosis. As the development of novel efficient diagnosis and therapy of tuberculosis, the mortality rate of tuberculosis has decreased gradually to a low level. In order to tackle tuberculosis at an earlier stage, the accurate diagnosis and preventive therapy of LTBI case has become increasingly critical.As a traditional diagnostic method of LTBI, tuberculin skin test (TST) is prone to be affected by BCG vaccination and nontuberculosis mycobacteria infection (NTB). IFN-y release assay (IGRA) is a novel diagnosis of LTBI with high sensitivity and specificity, overcoming the shortcomings of TST. Presently, the acquisition of epidemiological data of LTBI is based on TST, and no data of LTBI based on IGRA are available. Hence, we conducted an epidemiological study of LTBI in general population from rural area of Dongtai County in Jiangsu Province using IGRA kits, in order to obtain the latest data of LTBI epidemic situation in China and related risk factors of LTBI.A total of2169volunteers were recruited in the study, with874males (40.30%) and1295females (59.70%) and the mean age was54.40±15.84. The BCG vaccination rate of the volunteer group was19.18%, and141volunteers (6.50%) were tuberculosis contacts.527volunteers were positive of LTBI, and the LTBI rate was24.30%(95%CI:22.49-26.10%). The LTBI rate among general population was positive related to age. With every ten-year increase of age, the average increase of LTBI rate was4.58%. The LTBI rate among male group was27.69%(95%CI:24.72-30.66%), higher than22.01%(95%CI:19.75-24.26%) among female group (P=0.002). The LTBI rate among BCG-vaccinated group was26.01%(95%CI:21.78-30.22%), higher than17.07%(95%CI:15.31-18.83%) among BCG-umvaccinated group (P<0.001). The LTBI rate among group with tuberculosis contact history was41.13%(95%CI:32.95-49.30%), higher than23.13%(95%CI:21.29-24.97%) among group without tuberculosis contact history (P<0.001).We also analysed the relationship between gender, age, BCG vaccination, tuberculosis contact history between LTBI risk, respectively. Multi-factor logistic regression analysis revealed that three factors were LTBI risk factors, including gender (female/male, OR:0.79,95%CI:0.64-0.79, P=0.035), age (≥50yrs/<50yrs, OR:2.11,95%CI:1.64-2.72, P<0.001), tuberculosis contact history (yes/no, OR:6.12,95%CI:1.59-23.50, P=0.01). However, BCG vaccination was not the risk factor of LTBI (no/yes, OR:6.12,95%CI:0.72-1.41, P=0.97). And the difference between uni-factor analysis and multi-factor analysis of BCG vaccination might be due to the uneven distribution of BCG-vaccinated volunteers among different age groups.The LTBI rate24.30%obtained from our study is lower than the average rate44.4%obtained from the TST-based national tuberculosis survey of China in2000. Our study has revealed that gender, age and tuberculosis contact history are all LTBI risk factors, but BCG vaccination not. The results of our study can be used to provide a valuable reference for tuberculosis prevention and control in China. |
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