Tuberculosis remains an important infectious disease for primary care physicians. Significant problems exist in recognizing and diagnosing active tuberculosis and in using correct treatment to prevent the development of multidrug-resistant tuberculosis. Recognizing and treating tuberculosis in patients with AIDS is a major challenge. The impaired immune response leads to a lack of common signs and symptoms and more difficulty in providing effective treatment.
Tuberculosis infection is caused by Mycobacterium tuberculosis, generally affecting the lungs but can occur at many locations in the body [Treatment of Tuberculosis Guidelines 4th ed.; 2009 (available at WHO/HTM/TB/2009.420)]. Multidrug-resistant tuberculosis is defined as M. tuberculosis resistant to isoniazid and rifampin. Extensively drug-resistant (XDR) tuberculosis is defined [MMWR 2006; 55(43):1176] as M. tuberculosis isolates resistant to isoniazid, rifampin, any fluroquinolone, and at least one of three injectable second-line drugs (amikacin, kanamycin, or capreomycin). Latent tuberculosis is exposure to M. tuberculosis without active disease. Primary tuberculosis infection is active disease due to M. tuberculosis. Secondary tuberculosis infection in patients previously sensitized to M. tuberculosis usually occurs as reactivation TB, but may occur with reinfection with a new strain of M. tuberculosis. Extrapulmonary tuberculosis refers to localized infection at a site other than the lungs, such as lymph nodes, pleura, kidney, genitalia, bones or joints, heart, nervous system (particularly meninges), any intraabdominal organ (particularly at terminal ileum and cecum), peritoneum, and pericardium.
Tuberculosis (TB) (see WHO Fact Sheet 104; reviewed Feb. 2013) is second only to HIV/AIDS as the greatest killer worldwide, due to a single infectious agent even though the TB death rate dropped by 41% between 1990 and 2011. In 2011, 8.7 million people contracted TB and 1.4 million died from it. Most TB deaths (>95%) occur in low- and middle-income countries, and it is among the top three causes of death for women aged 15–44. In 2010, approximately 10 million children were orphaned as a result of TB deaths among parents. TB is a leading killer of people living with HIV, causing 25% of all deaths in this group of people.
Tuberculosis occurs in every part of the world. In 2011, the largest number of new TB cases occurred in Asia, accounting for 60% of new cases globally. However, sub-Saharan Africa carried the greatest proportion of new cases per population with over 260 cases per 100,000 people. Multidrug-resistant TB (MDR-TB) is present in virtually all countries surveyed.
In 2012, a total of 9951 new TB cases were reported in the United States, with an incidence of 3.2 cases per 100,000 population. However, the rate of TB increased in certain minority populations in United States. For instance, in 2012 the rate of TB among non-Hispanic Asians was 25 times greater than that among non-Hispanic whites, 7.3 times greater among ...