Abstract:

Objective: To evaluate the latent tuberculosis infection prevalence among tuberculosis (TB) contacts across various regions with different TB burdens by utilizing different screening technologies and strategies. Methods: We screened studies by searching the Chinese Journal Full-text Database, Web of Science, Medline and Embase, selecting studies based on predetermined inclusion and exclusion criteria. A total of 214 articles were enrolled, 33 articles were used for extracting secondary incidence rate of tuberculosis and all articles provided prevalence of latent TB infection. Studies were categorized by study areas, screening techniques and screening strategies, respectively, then a meta-analysis was conducted to calculate and compare the prevalence of TB and latent tuberculosis infection among contacts of patients. Results: The prevalence of latent TB infection was 12.0% (95%CI: 9.0%-16.0%) among contacts from high TB burden settings, higher than those living in low-burden countries (7.0%, 95%CI: 5.8%-11.0%). Prevalence of latent infection detected by tuberculin skin test was higher than that detected by IFN-γ released assay (41.0%, 95%CI: 33.0%-49.0% vs. 36.0%, 95%CI: 26.0%-45.0%). Among contacts of smear-positive patients, the prevalence of latent infection was 34.0% (95%CI: 23.0%-45.0%), compared to 20.0% (95%CI:10.0%-30.0%) among the contacts of smear-negative patients. The prevalence of latent infection among household contacts was 24.0% (95%CI: 16.0%-33.0%), higher than that of the general population (13.0%-20.0%). The secondary incidence rate among close contacts aged under 15 years was as high as 4.6% (95%CI: 2.6%-7.1%), which exceeded those observed in individuals aged 15 to 60 years (2.6%, 95%CI: 0.9%-4.3%), and those over 60 years (3.3%, 95%CI: 0.9%-4.3%). The prevalence of latent infection among population aged above 60 years old was 31.0% (95%CI: 0.9%-60.0%), higher than that in children <15 years of age (25.0%, 95%CI: 18.0%-33.0%). Conclusion: In countries with a high burden of tuberculosis, the targeted screening strategies in close contacts of smear-positive patients and household contacts, constitutes an effective approach for early identification of tuberculosis cases. Children and the elderly should be the focus of screening.

Key words: Tuberculosis, Mycobacterium infections, Contact tracing, Meta-analysis as topic