Lecture19 - 4/1/11 Lecture 19 The Evolution &...

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4/1/11 1 Lecture 19 • Useful summary reference: Gagneux S & Small PM. (2007). Global phylogeography of Mycobacterium tuberculosis and implications for tuberculosis product development. Lancet Infect.Dis . 7 , 328-337. • ~8 million people develop active TB every year, with 2 million dying from the disease (1 every 15 seconds). Also, up to 2 billion people have been infected with Mycobacterium tuberculosis . • TB is the world's leading infectious killer of young and middle-aged adults, causing 26% of avoidable deaths in the developing world. • TB is among the 7 leading causes of lost Disability-Adjusted Life Years (DALYs) well into the 21st century. The Global TB Pandemic • More than 90% of TB cases and 98% of TB deaths occur in the developing world. The annual risk of TB infection in Sub-Saharan Africa is more than 50 times the rate in Western Europe. In India alone, one person dies of TB every minute.
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4/1/11 2 New TB Cases in 2005 • 8.8 million new cases in 2005 (7.4 million in Africa and SE Asia) • 1.6 TB deaths (195,000 also had HIV) TB and HIV • An estimated 30 million people have died during the 1990s. WHO estimates that 2 billion people - one third of the world's population - are already infected with the tubercle bacillus and at least 5 to 10% will become ill in coming years. • Mathematical models predict 225 million cases and 80 million deaths from TB over the next three decades.
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3 TB Among Young Adults in the UK • TB is a highly infectious airborne disease caused by the bacterium Mycobacterium tuberculosis . Crowded homes and congregate settings (such as shelters, hospitals, and prisons) tend to foster transmission. • Although pulmonary TB is the most common form, the disease can affect virtually any organ (for example, lymph nodes, brain, and genitals). Classical clinical manifestations include coughing (sometimes bloody), fever, and weight loss. • The bacterium may remain dormant for years before it emerges as "active" disease. While activation of dormant infection is hard to predict, TB emerges most commonly among people with compromised immunity, such as those with malnutrition, diabetes, and HIV/AIDS infection. TB Epidemiology • Most people control initial infection by a cell-mediated immune response that prevents disease but can leave a residual population of viable mycobacteria. • Between 5 - 10% of individuals who become infected subsequently develop clinical disease. Primary TB develops within 1 or 2 years after an initial infection and is often associated with disseminated disease. • Post-primary TB develops later in life, caused either by reactivation of bacteria remaining from the initial infection or by failure to control a subsequent reinfection. • Post-primary TB is predominantly a pulmonary disease, involving extensive
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This note was uploaded on 05/03/2011 for the course BIOL 497A taught by Professor Eddieholmes during the Spring '08 term at Pennsylvania State University, University Park.

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Lecture19 - 4/1/11 Lecture 19 The Evolution &...

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