Introduction

The economic case for investment in tuberculosis (TB) control is compelling. TB control has been part of an essential package of health services for most low- and middle-income countries (LMICs) for decades, based on TB control's relatively high returns. The economic case, put simply, is that TB treatment is low cost and highly effective and on average may give an individual in the middle of their productive life around 20 additional years of life, resulting in substantial economic and health return. Yet, to date, globally TB control is underfunded, both in relative and absolute terms (Floyd et al., 2013). The most recent global estimates suggest a resource gap of around US$2 billion per year (World Health Organization, 2014), with TB receiving less than 4 percent of total development assistance for health (compared to HIV receiving 25 percent, and maternal and child health around 20 percent) in 2011 (Viz Hub).

Background

In 2010, TB was ranked 13th in terms of its contribution to the global burden of disease, primarily impacting LMICs and the world's poor (Lozano et al., 2012). Over 9 million individuals fell ill with TB in 2013, and the annual number of deaths from TB was estimated at 1_4 million persons in 2013, which is on par with other major killers such as HIV and malaria (Murray et al., 2014). Around 13 percent of the annual cases of TB and around 30 percent of all TB deaths are among persons living with HIV (Zumla et al., 2013). HIV increases the risk of mortality, and the presentation of TB in those living with HIV is atypical, meaning that TB, in those living with HIV, can be difficult to diagnose (Zumla et al., 2013).

TB has two stages: latent infection and active TB. Over two billion people worldwide are latently infected, and 5 percent of those develop active TB within 18 months, with a further 5 percent risk of developing active TB over a lifetime. The risk of developing the active form increases substantially after HIV infection. Most TB responds well to standard drug treatment, but there were almost half a million cases of multi-drug-resistant TB (MDR-TB) in 2013, with over 10 percent of these cases being extensively drug-resistant (XDR-TB) in some countries.