The resurgence of tuberculosis

Abstract

A lack of reliable statistics makes tuberculosis (TB) trends in developing countries difficult to estimate. Nonetheless, the World Health Organization and the International Union against Tuberculosis and Lung Disease estimated in 1990 that one-third of the world's population was infected with the tubercle bacillus and that there were 7-8 million new cases of TB annually. 95% of the new cases occurred in the developing world, with more than 5 million in Asia and the Western Pacific and more than 1 million in sub-Saharan Africa. Almost 80% of TB cases in developing countries occur among those under age 50 years. The global annual mortality was estimated at 2.5 million, with 98% of deaths occurring in developing countries. Worldwide, TB is believed to be responsible for 25% of avoidable deaths in young adults. There has been no significant decline in the average annual risk of infection in most developing countries due to incomplete coverage by control programs and inadequate cure rates. The interaction of HIV infection with TB is another factor which contributes to the deteriorating TB situation in many developing countries. Countries with a high population growth rate and little decline in the annual risk of infection should expect either a static or increasing level of TB disease. Immigration from developing countries, HIV infection, poverty, unemployment, homelessness, overcrowding, and population aging contribute to the spread of TB in developed countries. Drug resistance thwarts the control of TB worldwide.