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, over 10 million people develop active TB and 1.8 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. Among people living with HIV, TB incidence is much higher, and is the leading cause of death.
Diagnosis of pulmonary TB depends on a sputum sample, which can be difficult to obtain from children. A molecular test that can give results after just two hours and can detect a certain level of drug resistance is now being used, but it is costly and still requires a sputum 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 – can improve treatment outcomes for patients with drug-resistant versions of the disease, but their availability is currently limited.
MSF initiated 22,100 patients on treatment for TB in 2017, of which 3,600 for MDR-TB.