Drug-resistant TB Facts
- TB is second only to HIV/AIDS as the greatest killer worldwide due to a single infectious agent.
- In 2012, 8.6 million people fell ill with TB and 1.3 million died from TB.
- Over 95% of TB deaths occur in low- and middle-income countries, and it is among the top three causes of death for women aged 15 to 44.
- TB is a leading killer of people living with HIV, causing one fifth of all deaths.
- The TB death rate dropped 45% between 1990 and 2012.
TB is caused by bacteria (mycobacterium tuberculosis) that most often affect the lungs.
TB is curable and preventable.
TB is spread from person to person through the air. A person needs to inhale only a few of these germs to become infected.
When a person develops active TB (disease), the symptoms (cough, fever, night sweats, weight loss, etc.) may be mild for many months. This can lead to delays in seeking care, and result in transmission of the bacteria to others. People ill with TB can infect up to 10-15 other people through close contact over the course of a year. Without proper treatment up to two thirds of people ill with TB will die.
Common symptoms of active lung TB are cough with sputum and blood at times, chest pains, weakness, weight loss, fever and night sweats. Diagnosing multidrug-resistant TB (MDR-TB) and HIV-associated TB can be more complex. A new two-hour test that has proven highly effective in diagnosing TB, and the presence of drug resistance, is now being rolled out in many countries.
Active, drug-sensitive TB disease is treated with a standard six-month course of four antimicrobial drugs. They are also provided with information, supervision and support to the patient by a health worker or trained volunteer.
At least one third of people living with HIV worldwide in 2012 are infected with TB bacteria, although not yet ill with active TB. HIV and TB form a lethal combination, each speeding the other’s progress. Someone who is infected with HIV and TB is much more likely to become sick with active TB. In 2012 about 320 000 people died of HIV-associated TB. Approximately 20% of deaths among people with HIV are due to TB. In 2012 there were an estimated 1.1 million new cases of HIV-positive new TB cases, 75% of whom were living in Africa.
Standard anti-TB drugs have been used for decades, and resistance to the medicines is growing. Disease strains that are resistant to a single anti-TB drug have been documented in every country surveyed. Multidrug-resistant tuberculosis (MDR-TB) is a form of TB caused by bacteria that do not respond to, at least, Isoniazid and Rifampicin, the two most powerful, first-line (or standard) anti-TB drugs.
The primary cause of MDR-TB is inappropriate treatment. Inappropriate or incorrect use of anti-TB drugs, or use of poor quality medicines, can all cause drug resistance. Patients treated for MDR-TB are increasingly first-time TB patients, which means they were infected with the drug-resistant strain.
Disease caused by resistant bacteria fails to respond to conventional, first-line treatment. MDR-TB is treatable and curable by using second line drugs. However second-line treatment options are limited and recommended medicines are not always available. The extensive chemotherapy required (up to two years of treatment) is more costly and can produce severe adverse drug reactions in patients.
In some cases more severe drug resistance can develop. Extensively-drug-resistant TB (XDR-TB) is a form of multi-drug resistant tuberculosis that responds to even fewer available medicines, including the most effective second-line anti-TB drugs.
About 450 000 people developed MDR-TB in the world in 2012. More than half of these cases were in India, China and the Russian Federation. It is estimated that about 9.6% of MDR-TB cases had XDR-TB.