Tuberculosis

Tuberculosis (TB) is a bacterial infection caused by the pathogen Mycobacterium tuberculosis. Infection is transmitted person to person via the airborne route through inhaling infected aerosols. Affected individuals are often completely asymptomatic with the only evidence for infection found on routine screening for TB using skin or blood tests, a condition referred to as latent TB infection. Individuals with latent TB infection have a lifelong risk of developing active TB disease. The most common clinical manifestation of active disease is pulmonary tuberculosis. Disseminated disease involving the hematogenous spread of infection to the central nervous system, genitourinary tract, or bones and joints is most common at the extremes of age and among individuals with compromised immune systems, particularly in those living with human immunodeficiency virus infection. Active TB disease requires treatment with a combination of antibiotics for a prolonged period. The only available vaccine, bacille Calmette-Guérin or BCG, has been shown to be effective in preventing disseminated disease in young children but has little or no impact on preventing pulmonary tuberculosis in adults. The infection poses an enormous burden on society and public health due to its high prevalence, high level of contagion, chronic progression, requirement for prolonged treatment courses, and high rates of emerging antibiotic resistance. BCG vaccine plays an important role in the prevention of disseminated disease in young children but is not effective as a public health tool to reduce the overall global burden that this infection poses. Until safe and effective vaccines are available for the prevention of all forms of TB infection across all groups, the best control measures include early detection and treatment, programs to ensure adherence to treatment regimens, and comprehensive contact tracing to identify individuals who have been exposed to active disease.