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Background on Infectious Disease
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6 obligatory steps for microorganisms
Attachment with or without entry into the body
Logal or general spread within the body
Multiplication
Evasion of host defenses
Shedding from the body (exit)
Cause damage in the host
What is the main reason that microbes are always a step ahead of the host's immune system?
Microorganisms are evolving at a much faster rate compared to most host organisms.
They multiply quickly due to very short generation time.
They also have horizontal gene transfer including antibiotic resistance genes.
4 main types of infection classified by characteristics of the microbe.
Microbes with mechanisms for invading host body surfaces. - Viruses, certain bacteria.
Microbes transferred via biting arthropods. - malaria, plague, typhus, yellow fever.
Microbes transferred via skin wounds or animal bites. - Clostridia, rabies
Microbes that are opportunistic and are only able to attack when the host's defenses are down.
4 main steps in Koch's postulates
1. The suspected pathogen should be present in all cases of the disease and absent from healthy animals.
2. The suspected organism must be grown in pure culture.
3. Cells from a pure culture are introduced in to a healthy animal.
4. The suspect organism must be reisolated and shown to be the same organism.
Exceptions to Koch's Postulates
Some microbes cannot be cultured in the lab -
Treponema pallidum
, viruses
For some microbes there are no susceptible nonhuman hosts.
Author
smourer
ID
239559
Card Set
Background on Infectious Disease
Description
Terms and concepts related to the background of infectious disease.
Updated
2013-10-08T20:25:54Z
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