Childhood Tb: Global Epidemiology and Impact of HIV

Introduction

Although it is recognized that children make up a substantial proportion of the global tuberculosis burden, they remain a neglected group with low priority in TB control programs as well as in research and development. Difficulties in diagnosis coupled with limited research and surveillance data are major hurdles in estimating the true burden of TB disease in children. While adults are the major source of all TB in children, there is insufficient data on the transmission of TB from children and adolescents, especially those with smear and/or culture positive disease. Not enough attention has been paid to reducing transmission from infectious patients as well as in addressing other underlying determinants of disease such as malnutrition, indoor air pollution, and passive smoking. Despite childhood TB being both preventable and treatable, it still contributes substantially to morbidity and mortality in children under 5 years, in high TB burden countries. Further, TB in children serves as a good marker of TB control, indicating continued transmission within the community.

Abstract

Tuberculosis (TB) is still one of the deadliest infectious diseases in the world killing nearly two million people every year, mostly in developing countries where the prevalence is closely linked to poverty and malnutrition. Tuberculosis continues to be an important cause of morbidity and mortality among children worldwide, contributing 10–15% of all incident cases. Challenges in estimating the burden of childhood TB include the difficulty in establishing a definitive diagnosis, the higher prevalence of extrapulmonary disease (compared to adults), and the lower public health priority it has received. In high human immunodeficiency virus (HIV) prevalent settings, children (both infected and affected) are at high risk of TB infection due to close proximity with young adults who are most likely to be HIV-infected and in whom TB is the commonest opportunistic infection. Further, due to the high prevalence of other opportunistic infections among HIV-infected children and the lack of a gold standard, diagnosis of TB is often a challenge in this population. Bacilli Calmette-Guérin (BCG), despite its variable efficacy in different populations, is still the most widely used preventive measure against TB, but has safety concerns in HIV-infected infants. In the long-term, the burden of childhood TB can be reduced by effectively diagnosing and treating all infectious TB patients in the community, within a strong control program. In the meantime, more attention needs to be given to contact tracing and screening of household contacts of adult infectious patients, with provision of preventive therapy to all eligible children. Treatment of children with latent TB infection would also serve to reduce the pool of individuals from which future TB could arise. Additional efforts are needed to test and validate new diagnostic tools and strengthen surveillance systems for more reliable data on TB in children.

Keywords

childhood TB, HIV, epidemiology, contacts, risk factors