ealth programs in the United States, including those for the prevention and treatment of TB, was drastically curtailed in the 1980s. VI. Current Prevalence of TB Print section As the incidence of TB continued to decline in the early 1980s, most medical experts expected that the disease would be completely eliminated in industrialized nations by the year 2010. But by the mid-1980s, the number of TB cases began to increase—between 1985 and 1991, the number of reported cases in the United States increased 20 percent. Worldwide the incidence also skyrocketed in this period, and by the year 2000, the TB bacteria had infected more than one-third of the world's population.Multiple factors contribute to the global increase in TB. Infection with the human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS), is the single greatest risk for progression of TB infection to disease. People with HIV have weakened immune systems that increase their susceptibility to TB, and in these people, TB often progresses rapidly from the primary to the secondary stage. The increase of TB incidence is highest in Africa and Asia, areas with the highest number of people infected with HIV. 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...
