Tuberculosis (TB) is an airborne bacterium that can spread to any organ of the body, but most often is found in the lungs. Symptoms may include severe and prolonged coughing, fever, weight loss, chest pain, and night sweats.
Standard treatment regimens (first-line) for TB last six to nine months and are generally administered under the direct observation of a healthcare worker according to the WHO recommended DOTS strategy. Even under DOTS, people frequently find it difficult to adhere to such a long, rigorous course of treatment, which often requires isolation from families and friends to prevent contamination.
Multidrug-resistant tuberculosis (MDR-TB) compounds the challenges associated with TB treatment. It is defined by the Centers for Disease Control and Prevention as resistance to at least two of the first-line anti-TB medicines which are the first line of defense against TB. MDR-TB often develops in patients who are unable to properly complete treatment for regular TB, are taking less-than-quality assured medicines, who have failed first-line treatment or who have contracted the disease unknowingly. When first-line TB medicines are found to be ineffective and drug-resistance is diagnosed, patients require second-line anti-TB medicines. They will then need to take as many as 5-7 different medicines for up to 24 months. WHO reports that in the 27 high burden countries, on average, drug-resistance accounts for 21% of retreated TB cases. The inability to comply with treatment for MDR-TB can lead to even more resistant forms of the disease, including extensively drug-resistant tuberculosis (XDR-TB), and there are increasing reports of an alarming rise in the number of XDR-TB cases that do not respond to any current anti-TB medicines.
There is new hope with the development of sophisticated diagnostic tools and the recent arrival of new drugs, but significant human resources are still required to oversee treatment and adherence in countries where healthcare workers may be scarce. People hospitalized for the initial treatment period can increase the risk of MDR-TB transmission to staff and patients, particularly those already affected by HIV/AIDS, or where poor infection control measures are in place. There is an urgent need for additional training of healthcare workers on the prevention of transmission of TB within healthcare facilities, as well as training in diagnosis, treatment and care, and monitoring of resistance.
MDR-TB infection rates continue to rise. Despite being preventable and curable, MDR-TB remains a global crisis (as defined by the WHO). Because TB cannot be eliminated by medicine alone, a comprehensive strategy is needed to address multiple social, economic and medical issues simultaneously.
« TB is also a leading killer of people with HIV. People who are HIV-positive and infected with TB are 20 to 40 times more likely to develop active TB than people not HIV-positive living in the same country. »
Extensively Drug-Resistant Tuberculosis (XDR-TB)
XDR-TB is tuberculosis that is resistant to all first-line and some second-line medicines. In 2006, the U.S. Centers for Disease Control and Prevention and the WHO announced the worldwide emergence of XDR-TB after an outbreak in South Africa first captured international attention. No official estimates have been made on the number of XDR-TB cases, but some reports place the number at around 25,000 cases per year, most of them fatal. Since XDR-TB was first defined in 2006, 84 countries have reported at least one case of XDR-TB.