Epidemiology: Who Develops Pulmonary TB? How Does an Understanding of Global TB Epidemiology Help Clinicians Manage their Patients with Pulmonary TB?

Epidemiology of TB provides important information for clinical diagnosis. The risk of TB infection and disease development depends on exposure to bacilli, i.e., contact with infectious TB patients, host factors such as comorbidities, and socio-economic conditions. TB was called as the “white plague” in Western countries and “nation’s disease in Japan” because of its high mortality. Improvements in social conditions and the introduction of effective anti-TB drugs dramatically reduced the burden of the disease in such countries; however, the global annual incidence remains to be approximately ten million and the total number of deaths is 1.4 million mainly in developing countries. Major global challenges for TB control include HIV-associated TB, multidrug-resistant TB, migrant issues, and the elderly population. Since the 1990s, the World Health Organization (WHO) has strengthened TB control with the DOTS strategy, followed by the Stop TB Strategy and the End TB Strategy. The targets of the End TB Strategy are: (1) to reduce the incidence rate of TB by 90% by 2035, (2) to reduce the absolute number of TB deaths by 95% by 2035, and (3) to eliminate catastrophic costs faced by TB-affected families by 2020.