Abstract:

Objective: To analysed the screening of latent tuberculosis infection (LTBI) and the morbidity influencing factors in household contacts of positive and sensitive pulmonary tuberculosis (PTB) patients in Putuo District, Shanghai. Methods: This was a prospective study, the study subjects were the household contacts of positive and sensitive PTB patients who tested for Mycobacterium tuberculosis infection by γ-interferon release test in Putuo District from 2018 to 2021. After the first screen, the household contacts were followed up and tested for LTBI voluntarily within 3, 6, 12 months to calculate the cumulative infection rate. Binary logistic regression were used to analyze the risk factors of index cases on the LTBI of household contacts. The new cases were identified through the Tuberculosis Registration and Reporting System and short-term (end 202-12-03) incidence density of TB in household contacts were calculated. Results: From 2018 to 2021, a total of 168 PTB cases and 284 household contacts were enrolled in the study. The infection rate of the first screening test was 26.8% (76/284) and the cumulative infection rate was 34.5% (98/284) within one year. The results of multivariate analysis showed that the positive 2-month sputum examination of index cases was a risk factor for LTBI in household contacts (OR=7.167, 95%CI: 2.399-26.587, P=0.001). The short-term incidence density of 284 household contacts was 6.94/1000 person-years with 720.17 observation person-years. Five new cases were detected among and the short-term incidence density was 6.94/1000 person-years (5/720.17 person-years). There were no significant difference in the incidence density of PTB between LTBI household contacts (15.76/1000 person-years (4/253.83 person-years)) and non-infected individuals (2.14/1000 person-years (1/466.34 person-years))(χ²=2.607, P=0.106). Conclusion: The infection risk was high in household contacts of PTB patients. Index cases with positive 2-month sputum examination result had higher risks of generating LTBI. The timely diagnosis and effective treatment of smear-positive household contacts should be strengthened to effectively prevent the spread of tuberculosis in household contacts.

Key words: Tuberculosis, pulmonary, Latent tuberculosis, Family, Contact tracing, Multiphasic screening, Epidemiologic studies