The changing face of tuberculosis: a new challenge to the developing world.

The modern era of tuberculosis began in the mid 1980s. At that time it was realised that tuberculosis had not only ceased to decline in many developed countries, notably the USA, but was actually increasing. This forced health services to look more closely at the problem of tuberculosis. It was realised that the disease was out of control across most of the poorest regions of the world, especially Central Africa and South Asia. It was for this reason that in 1993 the WHO took the unique step of declaring tuberculosis to be a world emergency. Despite this intervention cases of tuberculosis are set to increase globally for the foreseeable future. One third of the world population, two billion people are infected with the tubercle bacillus It is estimated that deaths from tuberculosis will increase from 3 million a year currently to five million by the year 2050. There are four principal reasons for this