Tuberculosis

Abstract

Tuberculosis is caused by infection with Mycobacterium tuberculosis. It is a disease of considerable antiquity, well known in the ancient Indian and Greek worlds. Evidence of bone tuberculosis has been found in Chinese, Egyptian and pre-Columbian mummies. Tuberculosis has tended to be a disease of urbanisation and poverty. The conditions produced in the West by the Industrial Revolution were particularly favourable to its spread among an overcrowded and poorly nourished population. It was always one of the more common causes of death and in the 19th century it became one of the most important. In this century amongst the developed nations, with improvement in housing and nutrition, its incidence and mortality have declined. In England and Wales in the decade 1890–99 it caused 60 000 deaths/year. The notification rate in 1912 was 270/100 000, with a mortality rate of 50%. By 1980 the notification rate had fallen to 18/100 000; there were 9145 cases and 608 deaths. In the Third World there has been little or no change. The incidence remains very high and in some areas such as north-east Africa it is even increasing. Under these conditions mortality of sputum-positive tuberculosis remains high (about 50%) and tuberculosis is still a major cause of death. In the 1970s the annual risk of infection in Africa ranged between 2% and 5%, with 500 000 new cases of sputum-positive cases each year. The World Health Organisation estimated that in 1980 tuberculosis caused 1.25 million deaths − 5% of the total mortality, almost all in underdeveloped countries.