Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis. TB is contagious and spreads through the air. Symptoms of tuberculosis include a persistent cough, pain in the chest, coughing up blood or sputum, weakness, weight loss, chills, night sweats and fever.
Around two billion people, or one third of the world’s population, are estimated to be infected with the bacterium and at risk of developing the disease. Only a small proportion of those infected will become sick with TB. About 5% of infected people gets sick with tuberculosis in the first two years after infection. The other 95 % develops a latent or ‘sleeping’ infection, which is not contagious, but can still develop into TB later in life.
TB occurs in every part of the world. In 2013, the largest number of new TB cases occurred in the South-East Asia and Western Pacific Regions, accounting for 56% of new cases globally. However, Africa carried the greatest proportion of new cases per population with 280 cases per 100 000 population in 2013.
Bacille Calmette-Guérin (BCG), the only available TB vaccine, is administered to over 100 million babies every year and effective in preventing severe forms of TB in children. However, its efficacy against pulmonary TB – the most common form of TB worldwide – is poor or variable at best. New vaccines are urgently needed.
The overall lifetime risk for developing TB following infection is estimated to be approximately 10%. Pulmonary (lung) tuberculosis is the most common and most infectious form of TB worldwide. However, TB can attack any part of the body.
According to the latest data of the World Health Organization (WHO), there were 9 million new cases of TB in 2013. In 2013, around 1.5 million people died from tuberculosis, equaling about one death every 21 seconds.
The increased mobility of the world’s population, with more people traveling across borders, intensifies the spread of the airborne infectious disease. If not treated, each person with active TB infects on average 10 to 15 people every year.
Although poverty-related and mostly affecting developing countries (Africa and Asia), tuberculosis is prevalent in all continents. The situation is turning serious in Europe, is alarming in Africa and extremely worrisome in Russia, China and India.