One-third of the world’s population is currently infected with the tuberculosis (TB) bacillus but they have a latent form of the disease and so have no symptoms and cannot transmit it. In some people, the latent TB infection progresses to acute TB, often due to a weak immune system. Every year, about nine million people develop active TB and 1.5 million die from it.
TB is spread through the air when infected people cough or sneeze. Not everyone infected with TB becomes ill, but 10 per cent will develop active TB at some point in their lives. The disease most often affects the lungs. Symptoms include a persistent cough, fever, weight loss, chest pain and breathlessness in the lead-up to death. TB incidence is much higher, and is a leading cause of death, among people with HIV.
Diagnosis of TB depends on a sputum or gastric fluid sample, which can be difficult to obtain from children. A new molecular test that can give results after just two hours and detect a certain level of drug resistance is now being used, but it is costly and still requires a phlegm sample, as well as a reliable power supply.
A course of treatment for uncomplicated TB takes a minimum of six months. When patients are resistant to the two most powerful first-line antibiotics (isoniazid and rifampicin), they are considered to have multidrug-resistant TB (MDR-TB). MDR-TB is not impossible to treat, but the drug regimen is arduous, taking up to two years and causing many side effects. Extensively drug-resistant tuberculosis (XDR-TB) is identified when patients show resistance to the second-line drugs administered for MDR-TB. The treatment options for XDR-TB are very limited. Two new drugs – bedaquiline and delamanid – have recently become available to some patients who have no other treatment options left.
MSF treated 20,100 patients for TB, of which 2,000 for MDR-TB in 2015.