How frequent is latent tuberculosis infection in China?

In the Lancet Infectious Disease, Lei Gao and colleagues¹ report the results of a large multicentre, prospective cohort study of the prevalence of latent tuberculosis infection in China. The study was done in registered residents (aged ≥5 years) of four sites in rural China with diverse climates, population profiles, and incidences of tuberculosis. Eligible participants were identified by door-to-door survey and the screening process included a questionnaire about demographics and risk factors for tuberculosis, a tuberculin skin test, an interferon-γ release assay (QuantiFERON [QFT]), and digital chest radiography for participants older than 15 years.