Tuberculosis

A second factor contributing to TB resurgence is the failure of patients to complete the full six to nine months of antibiotic therapy required to cure the disease. Many people stop taking antibiotics when they begin to feel healthier, but successful treatment of TB requires therapy beyond the period of obvious symptoms. When patients fail to follow the prescribed treatment, they may become actively infectious, spreading the disease to others. An infected person may infect as many as 10 to 15 other people in a single year. Failure to complete the full round of treatment also can cause the emergence of TB bacterial strains with acquired drug resistance, further complicating treatment by increasing the length and cost of therapy.

The emergence of strains of bacteria that are resistant to multiple drug therapy is a serious problem, particularly because no drug treatment is available to combat newly emerging strains. To improve compliance, the World Health Organization (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, overcrowding, 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.