Transmissions of Infections Flashcards

1
Q

what are the steps of the chain of infection?

A
  • infectious agent
  • reservoirs
  • portal of exit
  • means of transmission
  • portal of entry
  • susceptible host
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2
Q

what is meant by virulence?

A

the ability of the microbe to cause disease

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3
Q

what is meant by dose?

A

• the number of microbes entering the body

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4
Q

what is dose normally expressed as?

A

infectious dose 50 (ID50)

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5
Q

how do you know if a microbe is MORE infectious?

A

a LOW ID50

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6
Q

what are exotoxins?

A

a toxin released by bacteria into the external environment

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7
Q

what is an endotoxin?

A

a toxin that is released from GRAM NEGATIVE bacterial cell walls

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8
Q

what is an example of a periodontal pathogen?

A

P. gingivalis

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9
Q

what is a leukocidin?

A

a white cell toxin

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10
Q

what is an enterotoxin?

A

a toxin produced in/affecting the intestines

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11
Q

give examples of reservoirs:

A
  • humans
  • animals
  • environment
  • contaminated surfaces
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12
Q

give an example of an environmental pathogen?

A

CLOSTRIDIUM TETANI spores in soil

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13
Q

what are the different phases of an infection?

A
  • patients in acute phase
  • patients in the prodromal phase
  • healthy carriers
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14
Q

what is meant by the incubation period of a pathogen?

A

the time between contamination and the development of symptoms

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15
Q

what do long incubation periods permit?

A
  • longer time periods when the infecting microbe may be spread to others
  • greater spread of the disease due to more human contact
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16
Q

what is an infected person that shows no clinical evidence the disease called?

A

asymptomatic carrier

17
Q

what is meant by colonisation?

A

the presence of the microorganism in/on a host with growth and multiplication but without overt clinical expression (infection)

18
Q

when is meant by an endogenous infection?

A

infection caused by members of the normal flora

19
Q

give an example of an endogenous infection:

A

periodontal disease

20
Q

what is meant by an exogenous infection?

A

infection caused by microbes from external sources

21
Q

give an example of an exogenous disease:

A

influenza virus

22
Q

modes of escape from the source can be?

A
  • natural

* artificial

23
Q

example of a natural mode of exit?

A

• coughing/sneezing

24
Q

example of an artificial mode of exit?

A

blood donation/dental hand piece aerosols

25
Q

what are the 4 hazard groups that human pathogens are classified into?

A
  • ability to cause infection
  • severity of the disease that may result
  • vaccine & treatment availability
  • risk of population spread
26
Q

what is meant by the “R” number?

A

the number of cases one case generates on average over the course of its infectious period

27
Q

what factors affect the “R” number?

A
  • duration of infectivity
  • infectiousness
  • number of susceptible people
28
Q

why are aerosols problematic in reverence to infection?

A

aerosols can aid in transmission

29
Q

how can aerosols in dentistry be mitigated in an attempt to slow down/prevent transmission?

A
  • use of rubber dams
  • high/low volume aspiration
  • surgery ventilation
30
Q

how long does Influenza A&B survive on steel and plastic?

A

24-48 hours

31
Q

how long does Influenza A&B survive on cloth, paper & tissues?

A

8-12 hours

32
Q

what are the 5 moments for hand hygiene within the practise?

A
  1. before touching a patient
  2. before clean/aseptic procedure
  3. after body fluid exposure
  4. after touching patient
  5. after touching patient surroundings
33
Q

give examples of human portals of entry:

A
  • respiratory tract
  • gastro-intestinal tract
  • open/surgical wounds
  • medical devices/sharps injuries
  • sexual contact
34
Q

why are susceptible hosts more at risk of infection?

A
  • underdeveloped immune system
  • declining immune system (elderly)
  • breaks in the skin
  • medical devices