31 - Chapter 31 Infection and Pathogenicity I Host-Parasite...

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Chapter 31: Infection and Pathogenicity I. Host-Parasite Relationships A. Infection= when a parasite is growing and multiplying within the host; varies with respect to severity, location, and # of organisms B. Infectious disease= change form a state of health in which part of all of the host body is not capable of carrying on its normal functions due to the presence of a parasite or its products C. Pathogen= organism or agent that produces a disease C.1. Primary pathogen= organism that causes disease in a healthy host by direct interaction C.2. Opportunistic pathogen= organism that infects a host having a weakened immune system (compromised host) D. Pathogenicity= ability to cause disease E. Latent state= no transmission of the organism occurs/not infectious at the time/no symptoms present within host E.1. Intermittent latency= after initial infection, symptoms subside; however parasite remains in the host and can be activated cyclically due to exposure to stress or UV (ex: herpesvirus cold sores) E.2. Quiescent latency= organism persists but remains inactive for long periods of time (ex: mycobacteria tuberculosis; varicella-zoster virus chickenpox) F. Factors that determine outcome F.1. Number of microorganisms F.2. Virulence=degree or intensity of pathogenicity F.3. Host’s defenses or degree of resistance II. Infectious Disease Process: incubation period=pathogen entry to development of signs and symptoms (pathogen is spreading but not reached sufficient level to cause clinical manifestation); prodromal state= onset of signs and symptoms (contagious but not able to make diagnosis); illness period=most severe (host immune response triggered); convalescence= signs and symptoms disappear (aka recovery) A. Source or Reservoir
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Chapter 31: Infection and Pathogenicity A.1. Source= location from which the pathogen is immediately transmitted
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This note was uploaded on 02/17/2012 for the course BIOL 351 taught by Professor Sig during the Fall '08 term at Texas A&M.

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31 - Chapter 31 Infection and Pathogenicity I Host-Parasite...

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