Introduction to Infection and Immunity Flashcards

1
Q

What are the three domains of the phylogenetic tree of life?

A

Bacteria
Archaea
Eukaryota

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2
Q

What are the Parasites?

A
Helmiths
Lice
Mites
Protists
Fungi
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3
Q

What are the microorganisms?

A

Protists
Fungi
Bacteria

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4
Q

What are the non-cellular agents?

A

Viruses

Prions

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5
Q

What do transmissible organisms move between species?

A
Ebola
HIV
BSE/nvCJD- cattle
Leprosy- between animals 
Tuberculosis
Ascaris
Measles- dogs
Influenza- birds
Schistosomes 
Malaria
Leishmaniasis
Plague- rats
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6
Q

What is mutualism?

A

Both members benefit

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7
Q

What is commensalism?

A

One benefits

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8
Q

What is parasitism?

A

One harms the other

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9
Q

What is pathogenicity?

A

The ability to cause disease

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10
Q

What is virulence?

A

The measure of pathogenicity

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11
Q

How do transmissible diseases cause disease?

A
Pass between hosts
Attach to and enter host
Survive the host's antimicrobial defences
Disperse within the host
Cause disease
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12
Q

What are the chain of events in an infectious disease?

A
Transmission
Entry
Attachment and colonisation
Multiplication in vivo
Evasion of host defence mechanisms
Damage to the host
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13
Q

What is transmission?

A
Whether or not disease occurs depends on many factors:
Pathogenic potential of infectious agent
Susceptibility of host
Way in which they encounter
Species 
Genetics (selection of ancestors)
Age
Gender
Nutritional status
Immune status
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14
Q

What is entry of an infectious disease?

A

Through local or systemic effects
Mucosal surfaces
Skin

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15
Q

How does infectious disease infect through mucosal surfaces?

A

Respiratory tract- Myobacterium tuberculosis, influenza virus
Gastrointestinal tract- salmonella typhi, poliovirus
Genitourinary tract- Neisseria gonorrhoeae, HIV

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16
Q

How does infectious disease infect through skin?

A

Insect & tick bites- malaria, filariasis, typhus
Animal bites- rabies
Wound contamination- tetanus
Direct invasion- hookworms, schistosomes, myiasis
Contact- smallpox, measles, scabies

17
Q

In what ways does attachment and colonisation occur?

A

Competition with normal flora
Specific adhesion mechanisms to host receptors
Evade and survive barriers
Localised infection- establishment phase, followed by dissemination
Generalised/systemic infection or toxin spread from a localised site

18
Q

How does infection occur by multiplication in vivo?

A
The organism must find appropriate environmental conditions e.g. 
Nutrients
pH
Temperature
Aerobic/ anaerobic
19
Q

What are the steps of evasion of host defence mechanisms?

A

Innate (non-specific)
Adaptive (specific) immune mechanisms
Evasion necessary until preferred site of infection is reached or for long enough to complete the cycle in the host and to ensure spread to fresh hosts
Manipulation of host immunity

20
Q

In what ways can damage to the host occur?

A

Direct damage by infectious agent
Indirect damage via inflammation
Indirect damage via immune response

21
Q

What ways can direct damage happen?

A

Multiplication within and destruction of host cells

Exotoxins

22
Q

How does multiplication within and destruction of host cells cause direct damage?

A

Viruses- poliovirus/neurones
Some bacteria- mycobacterium tuberculosis/macrophages
Some protists- plasmodium/erythrocytes

23
Q

How do exotoxins cause direct damage by infectious agent?

A

Promoting survival or spread- hyaluronidase S. aureus
Damaging or destroying cells- leucocidin S. aureus
Interfereing with cell metabolism- diphtheria toxin
Affecting passage of nerve impulses- tetanus toxin

24
Q

In what ways can indirect damage via inflammation cause damage to the host?

A

Inflammatory response is an important part of host defences
Over activity can damage the host’s own tissues
Inflammatory mediators:
1.From cells damaged by infection
2.From some pathogens
3.From cells of the innate immune system

25
Q

In what ways can indirect damage via immune response cause damage to the host?

A

Immune response is a vital part of host defences- over activity (hypersensitivity) can cause tissue damage (immunopathology)

26
Q

What are the confounding factors in controlling and eliminating transmissible diseases?

A

Drug and vaccine development- feasibility, time, cost
Human behaviour
Social disruption and warfare
‘Alternative’ and ‘traditional’ medicine
Pathogen ingress to human population from other species
Pathogen evolution
Climate and environmental change
Politics, sociology, religious and cultural beliefs, false information

27
Q

Why can pathogens continue to circumvent our immune system?

A

They evolve and adapt to our drugs and vaccines

28
Q

What are some examples of pathogens who have evolved to continue to harm?

A

Myxoma virus
Syphillis
Influenza virus