Microbiology and Immunology 2500A/B Lecture Notes - Genitourinary System, Propionibacterium Acnes, Helicobacter Pylori
21 Sep 2012
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Document Summary
The major cause of human mortality throughout history. Major increases in life expectancy from early 1900s mainly due to control of infectious disease. In large populations, an infectious disease may be able to find a continuous supply of new hosts and becomes endemic i. e. continuously present. However, diseases in small populations cannot find sufficient new hosts and. In smaller populations after a disease burns itself out, the non-immune population gradually builds up and may become infected from outside to produce an epidemic i. e. affecting many people at the same time. An epidemic on an inter-continental scale is called a pandemic. Do infectious agents evolve to become more virulent. New infections may produce a high death rate, but over the course of time the host and agent adapt to one another and the disease normally becomes less virulent. Modern medicine has studied microbes as perpetrators of disease. However, the vast majority of microorganisms are not pathogenic.
