Tuberculosis (TB) is an ancient disease; suggestive spinal changes have been described in Neolithic man, and clear evidence of TB bone lesions have been found in mummified remains from Egypt.1 Hippocrates (460–377 BC) introduced the ancient Greek term for TB, phthisis, better known as consumption.1 Although TB is an ancient disease, it remains one of the major public health challenges of the new millennium. Fuelled mainly by rampant third world poverty and the human immunodeficiency virus (HIV) epidemic, TB affects and kills more people today than ever before. The gravity of the situation is reflected by (1) the fact that the epidemic continues to escalate despite the declaration of a global TB emergency by the World Health Organization (WHO) in 1993 and (2) the increased transmission of drug-resistant TB.
Robert Koch (1843–1910) discovered that Mycobacterium tuberculosis causes TB, but it was soon recognized that infection, as indicated by a positive tuberculin skin test (TST), is not at all uncommon. It remains an intriguing and largely unexplained observation that only a small minority of people infected with M. tuberculosis ever progress to active disease. In endemic countries, TB control programs focus on the diagnosis and treatment of the most infectious cases (adults with sputum smear-positive TB) in an attempt to control the epidemic. Childhood TB receives little public health emphasis, as children tend to have paucibacillary disease and rarely transmit the organism. However, children in endemic areas carry a huge disease burden and experience considerable TB-related morbidity and mortality.2,3 In addition, adolescent children frequently develop cavitary disease4 and contribute to disease transmission within the community, particularly in congregate settings such as schools.5
An estimated 8.3 million new TB cases were diagnosed in 2000, of whom 884, 019 (11%) were <15 years of age.6 Poor countries carry the bulk of the TB disease burden, as exposure to both the organism and the vulnerability to progress to disease following infection are increased in these settings (Figure 36–1).7 HIV-related immune compromise is the most important factor that increases the vulnerability of individuals to develop TB following exposure and infection, which explains why Sub-Saharan Africa, the region worst affected by HIV, reports the highest TB incidence rates in the world.8
The main variables that contribute to the prevalence of TB in adults and by extrapolation the burden of childhood TB. (With permission from Marais BJ, Obihara CC, Warren RM, Schaaf HS, Gie RP, Donald PR. The burden of childhood tuberculosis: A public health perspective. Int J Tuberc Lung Dis. 2005;9(12):1305–13.)
The risk to develop active TB following infection is mainly determined by the age and immune status of the child.9 The highest risk occurs in very young (immune immature) and/or immune-compromised children (Table 36–1).9 If children do progress to active TB, ...