strains of bacteria that are resistant to multiple drug therapy is a serious problem, particularly because no ready drug treatment is available to combat newly emerging strains. To improve compliance, the WHO strongly recommends that all countries, especially those in Africa and Asia, adopt a program called directly observed treatment, short-course (DOTS). DOTS requires health workers to monitor patients to make sure that they follow the complete course of treatment. The success rate and the cost effectiveness of this program have been proven around the world. Epidemics in New York City, Tanzania, Peru, and China in the early 1990s were brought under control using DOTS. Migration, international air travel, and tourism also have contributed to the global spread of TB. The extreme difficulty of screening immigrants and travelers for TB allows the disease to cross international borders easily. The substantial increase in homelessness, and the related circumstances of poverty, crowding, and malnutrition, also contributed to the increased incidence of TB in the United States and other industrialized countries during the early 1990s. While industrialized nations with good public health systems have been able to control the recent TB resurgence, curbing the spread of TB on a global scale will require ongoing international efforts. In the future, combating TB throughout the world will require advances in molecular biology, research into the genetics of TB in order to understand drug resistance, and the continuous development of new drugs, as well as the prospect of synthesizing additional vaccines. Incidence of Tuberculosis, United States This graph illustrates the number of new cases of tuberculosis in the United States since 1985. Many researchers attribute the sharp increase in the early 1990s to the spread of acquired immunodeficiency syndrome (AIDS). People with AIDS have weakened immune systems and are particularly susceptible to conta...
