Microbiology 474 -5 -Infection and disease

  1. What is the difference between imtermediate and definite host ?
    Definitive (Final) host:–Maintains the mature form of the parasite–Maintains the sexually reproductive form of the parasite•

    -Intermediate host(s):–Maintains the immature parasite–The immature parasite usually undergoes various stages of development before being transferred to the definitive host.
  2. What is the difference between endoparasite and ectoparasite ?
    Ectoparasite: organism that lives on the surface of a host

    Endoparasite: organism that lives on the inside of the host
  3. What is the difference between exogenously and endogenously aquired parasite ?
    •Exogenously acquired infections results from encounters with pathogens in the environment–Endogenous

    •Endogenously acquired infections are caused by pathogens or potential pathogens in or on the body.
  4. Difference between intracellular pathogens - obligate and facultative ?
    •Obligate intracellular pathogen–Will not grow outside of a living eucaryotic cell–Are not free living

    •Facultative intracellular pathogen–Can be free living
  5. What is pathogensis ?
    The process by which microbes cause disease in a host.•The steps involved in disease progression within the host.
  6. What is pathogenicity ?
    Pathogenicity•the ability of microbes to cause disease•the capacity of a pathogen to invade and harm a host
  7. what are pathogenicity islands ?
    Pathogenicity islands–Large segments of DNA that code for virulence factors; often acquired during horizontal transfer–Clusters of pathogenicity genes encoding virulence factors•Exceptions:Plasmids, prophages
  8. What is virulence ?
    Virulence–the degree or intensity of pathogenicity–the measure of the severity of a disease–The degree of harm to the host
  9. What are virulence factors ? Name some ?
    Virulence Factors–Products of microbes that increases the invasiveness or pathogenicity of the organism–Examples:•Toxins•Enzymes•Capsules•FlagellaHost-Pathogen Interactions
  10. What is the difference between Lethal dose and Infectious dose ?

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    Lethal dose (LD50): the number of pathogens that kill 50% of hosts within a specified period of time; often associated with toxin production

    •Infectious dose (ID50): the number of pathogens that infect 50% of hosts within a specified period of time
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Microbiology 474 -5 -Infection and disease