ABSTRACT

A quarter of the world's population may be infected with tuberculosis (TB). In the majority of these people the infection will remain dormant. A variety of risk factors may lead to this latent TB infection (LTBI) becoming active. Treatment of LTBI has been shown to reduce the risk of developing active TB. Good evidence exists for the efficacy of treating LTBI in preventing individuals from progressing to active disease. Daily isoniazid was the first agent to be shown to be effective in preventing LTBI from progressing to active TB in a number of large studies. RIF monotherapy has been shown to reduce the incidence of TB compared to placebo by approximately 50% in an initial study in Hong Kong. Intravenous drug users have been shown to have a higher risk of developing active TB compared to the background population. Silicosis has long been recognized as a risk factor for developing pulmonary TB.