children and adolescents can transmit Mycobacterium tuberculosis and so contribute to disease propagation, and children infected with M. tuberculosis provide a reservoir for future disease. Thus, addressing child and adolescent TB is essential in the fight towards TB elimination. After years of neglect, child and adolescent TB is finally gaining more attention in global TB efforts. A key focus of the WHO’s global End TB Strategy is to end the TB epidemic by 2030, including diagnosing and treating at least 90% of children with TB [1]. At the 2018 United Nations High-Level Meeting, a global target was also set to diagnose and treat 3.5 million children with TB by 2022. By the end of 2021, only 1.9 million (54% of the target) had been treated in the years 2018–2021. A target was also set to offer TPT to 4 million children 5 years of age who are at risk of developing TB by 2022 [2]. However, over the period 2018–2021, only 1.6 million children (40% of the target) had been offered TPT. In this chapter, we will discuss the diagnosis and treatment of TB in children and will highlight recent developments. We will end by identifying research priorities in the field. Epidemiology and natural history Burden of paediatric TB TB in children (15 years) represents 11% of the global TB burden, but this figure can be higher in high-TB-burden countries. Typically, high-TB-burden countries have 40–50% of their population aged 15 years, and given the high frequency of exposure to M. tuberculosis, children are more likely to be exposed at a younger age, when TB progression is more likely [3]. It was only in 2012 that the WHO produced the first child-specific estimates of incidence and mortality for child TB [4]. Initially, the WHO used burden estimation methodology similar to that used in adults with the same estimated case detection rate. However, in recent years, more sophisticated ensemble modelling approaches have been used [5]. Modelling studies have estimated that 67 million children (15 years) were infected with M. tuberculosis worldwide in 2014 [6], and the 2022 WHO TB report estimated that, of these, 1.2 million developed TB disease in 2021 [2]. Over half of these children are not reported, with the highest case-detection gap (69%) in children 5 years [7]. This is mainly a result of continuing limitations in available screening and diagnostic measures for children exposed to TB, health worker capacity and their confidence to diagnose children with TB, the paucibacillary nature of the disease in this population, challenges in accessing health services [8, 9] and recently the COVID-19 pandemic [2, 10]. In 2021, an estimated 209 000 children 15 years of age died of TB, and modelling studies suggest that 96% of child TB deaths occur in children who were undiagnosed. Most of these deaths occur in children 5 years, an age with a higher risk of severe disease and mortality, and the group with the most profound diagnostic challenges [2, 11, 12]. Estimates for MDR-TB (disease caused by M. tuberculosis resistant to at least isoniazid and rifampicin) suggest that ∼30 000 children develop the disease each year [6, 13]. Only one-fifth of these are diagnosed, treated and reported to the WHO [2]. Reliable estimates of childhood TB disease burden are difficult to make due to diagnostic limitations and deficient recording and reporting, as well as limitations in the method used to calculate estimates from the number of reported cases [14]. Suggested best practices for improving reporting and recording include individual-level participant electronic registries, integration of TB services in child health services, integration of databases at the multiple entry points and engagement of different sectors involved in TB care (private sector and nongovernmental organisations) [15–18]. https://doi.org/10.1183/2312508X.10025322 211 CHILDREN AND ADOLESCENTS |E. LÓPEZ-VARELA ET AL.