Latent tuberculosis infection among close contacts of positive etiology pulmonary tuberculosis in Chongqing

Abstract:

Objective To investigate the current situation and influencing factors of latent tuberculosis infection (LTBI) among close contacts of positive etiology pulmonary tuberculosis (PTB) patients, provide basis for formulating intervention measures for LTBI. Methods A multi-stage stratified cluster random sampling method was used to select close contacts of positive etiology PTB patients from 39 districts and counties in Chongqing City as the study objects. Demographic information was collected by questionnaire survey and the infection of Mycobacterium tuberculosis was detected by interferon gamma release assay (IGRA). The influencing factors of LTBI were analyzed by χ² test and binary logistic regression model. Results A total of 2 591 close contacts were included, the male to female ratio was 0.69:1, with the mean age of (35.72±16.64) years. 1 058 cases of LTBI were detected, Mycobacterium tuberculosis latent infection rate was 40.83%. Univariate analysis showed that the infection rate was different among peoples of different age, body mass index (BMI), occupation, education level, marital status, whether they had chronic disease or major surgery history, whether they lived together with the indicator case, and whether the cumulative contact time with the indicator case ≥ 250 hours, difference were all statistically significant (all P < 0.05); infection rate presented increased trend with the increase of age and BMI (both P < 0.001), and decreased trend with the increase of education (P < 0.05). Logistic regression analysis showed that age 45-54 years old (OR=1.951, 95%CI: 1.031-3.693), age 55-64 years old (OR=2.473, 95%CI: 1.279-4.781), other occupations (OR=0.530, 95%CI: 0.292-0.964), teachers (OR=0.439, 95%CI: 0.242-0.794), students (OR=0.445, 95%CI: 0.233-0.851), junior high school education or below (OR=1.412, 95%CI: 1.025-1.944), BMI < 18.5 kg/m² (OR=0.762, 95%CI: 0.586-0.991), co-living with indicator cases (OR=1.621, 95%CI: 1.316-1.997) and cumulative contact time with indicator cases ≥ 250 hours (OR=1.292, 95%CI: 1.083-1.540) were the influential factors for LTBI (all P < 0.05). Conclusion The close contacts with positive etiology PTB have a high latent infection rate of Mycobacterium tuberculosis, and it is necessary to pay attention to close contacts of high age, farmers, and frequent contact with patients, and take timely targeted interventions to reduce the risk of occurrence of disease.