Scaling-up symptom-agnostic, community-wide screening towards global tuberculosis elimination: opportunities, challenges and lessons from history.

There has been little change in global TB incidence in the 21 century. Although case notification has increased, millions of people with TB each year remain unreached. Recently there has been increased recognition that many people with undiagnosed, potentially infectious TB do not experience or report TB symptoms. Symptom-agnostic screening (e.g. by chest X-ray) can effectively identify such forms of TB. While this activity is increasing globally and is beneficial to individuals screened, current levels fall far short of what is needed to impact transmission and population-level prevalence. Significant scale-up of symptom-agnostic screening across communities is required to improve treatment coverage and interrupt transmission. While there are major political, financial and health system challenges to undertaking such scale-up this is not without precedent. In the mid 20 century, in many countries which now experience a low TB burden, population level chest X-ray screening was successfully undertaken and contributed to the decline in TB. In this article we explore the challenges and opportunities that face countries wanting to scale-up symptom-agnostic screening and reflect on important lessons from the past.