Chapter 70

Tuberculosis remains an important infectious disease in the world today; more than one third of the world’s population has tuberculosis. It causes 9 million new cases per year, with 2 million deaths per year.1 In fact, it is the second leading cause of death among infectious diseases. Worldwide, the number of cases continues to rise, especially in areas most affected by the human immunodeficiency virus (HIV) and socioeconomic depression.2 In the U.S., new cases of tuberculosis steadily declined from the late 1800s until 1984, followed by increases at alarming rates until 1992. Factors believed to be responsible for this resurgence of tuberculosis include an increase in the number of homeless persons, the HIV epidemic, drug abuse, increased immigration, and the inability of local and state governments to maintain tuberculosis control programs.3–5

From 1993 to 2005, tuberculosis was once again on the decline in the U.S., primarily due to stronger tuberculosis control programs that targeted high-risk individuals. In addition, improved infection control policies, increased vigilance among physicians, the implementation of directly observed therapy (DOT), and standardized drug regimens have all contributed to the decline of tuberculosis rates.3,5 In 2005, there were 14,093 cases of tuberculosis reported (4.89 cases per 100,000 population). This rate is 3.8% less than in 2004 and is also the lowest rate since 1953, when official national reporting of tuberculosis began.1

In the U.S., two major areas of concern in the epidemiology of tuberculosis have been noted. Although the reported rate of tuberculosis has consistently declined since 1992, the average rate of decrease each year from 2001 to 2005 was only 3.8% in comparison to an average of 7.1% in the previous 8 years. Also, the number of tuberculosis cases in foreign-born persons continues to be substantial, with the actual number of foreign-born persons with tuberculosis continuing to increase.1 In 2005, the percentage of tuberculosis found in foreign-born patients was 8.7 times that of U.S.-born persons.1 Studies suggest that tuberculosis in foreign-born patients tends to be secondary to reactivation of latent disease rather than recent acquisition of the infection.5,6

Continued improvement in tuberculosis control and prevention requires recognition and treatment of high-risk populations (Table 70-1) in decreasing order of risk), continued funding of programs for surveillance and treatment of noncompliant patients, aggressive screening of foreign-born persons, continued basic research into the pathogenesis and immunologic response, and continued development of new pharmacologic agents.3,4 A useful Web reference is http://www.who.int/tb/en.

Table 70-1 Patients with a High Prevalence of Tuberculosis

Mycobacterium tuberculosis is a slow-growing aerobic rod that has a unique, multilayered cell ...

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