FIRS The Global Impact of Respiratory Disease – Second Edition | Page 22

Prevention In no disease is the phrase “treatment is prevention” truer than with TB. The factors promoting the spread of infection relate to the chance that an uninfected individual is exposed to a person with infectious TB: the more cases in the community, the more likely it is that an individual will become infected. Factors promoting the development of disease in infected individuals generally relate to the function of the immune system. The most potent factor causing an exposed person to develop active tuberculosis is infection with HIV, but other conditions that affect immunity, such as certain medications and the presence of poorly controlled diabetes, also increase the risk of developing active disease. Inhaling only a few tuberculous bacteria can result in infection. However, only about one in 10 people infected with Mycobacterium tuberculosis will develop active disease, although the rate is much higher in young children and people with immunodefi ciency conditions. TB lies dormant because the infection is contained by the body’s immune system, but it can become active at any point in a person’s lifetime. This two-phase sequence by which the disease develops provides an opportunity for prevention. By identifying persons who are proven or are highly likely to have latent infection and treating those who have conditions or circumstances that increase the risk of disease, the likelihood of developing active TB can be substantially reduced. Several drug regimens have been documented to be effective for treating latent tuberculosis [35]. Treatment in all healthcare sectors and countries. The long duration of therapy (usually 6 months with four drugs in uncomplicated cases) makes adherence to treatment challenging, especially in individuals who are taking other medications for chronic diseases, such as HIV infection. Failure to take the full course of prescribed drugs appropriately may result in relapse with drug-resistant disease, which is more diffi cult to treat and poses a risk to others. For this reason, supervised or directly observed therapy is recommended as the standard of care to ensure adherence throughout the course of treatment. Most cases of TB can be cured if diagnosed early and treated appropriately using standardised approaches that are based on evidence derived from clinical trials. The International Standards for Tuberculosis Care [36] should be followed by providers Treatment of patients with multidrug-resistant TB is a more complicated issue. Although the standard has been to treat with fi ve or six drugs for 14–18 months, a recent trial has shown a shorter course of therapy is better [37] and now recommended by WHO. The current vaccine, Bacille–Calmette–Guérin (BCG), offers only partial protection against TB but does reduce the risk of disseminated TB and tuberculous meningitis in children. Research centres around the world are working on developing a better vaccine for TB. Forum of International Respiratory Societies 21