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Infection, immunity and repair > Infectious agents around the world > Flashcards

Infectious agents around the world Flashcards

1
Q

What is an infectious agent?

A

Agent that can replicate within or on another organism whose progeny can spread onward to new hosts

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2
Q

What causes the manifestation of disease pathology?

A

Invader fights host

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3
Q

What are 8 types of infectious agents?

A

Bacteria

Viruses

Fungi

Flatworms

Roundworms

Arthropods

Proctists

Prions

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4
Q

Characteristics of bacteria

A

Prokaryotic

Not all species are harmful - can reside as helpful commensals on body

Whether helpful/beneficial depends on time and place

Only agent susceptible to antibiotics

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5
Q

Characteristics of fungi

A

Significant infectious agents in immunocompromised patients

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6
Q

Characteristics of protozoa

A

Single-celled eukaryotes

All body compartments - spectrum of disease

Infect people intracellularly and extracellularly

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7
Q

Characteristics of roundworms

A

Nematodes

Broad class - thousands of species

50% of species = parasitic

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8
Q

Characteristics of flatworms

A

Large, segmented, highly organised invertebrates

Some reside parasitically within human host - host needed for transmission

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9
Q

Characteristics of prions

A

Infectious protein

Not alive

Replicates to cause pathology

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10
Q

How do prions cause pathology?

A

Converts normal proteins into prions

Causes protein misfoding of normal cellular proteins

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11
Q

Example of bacteria

A

E. Coli

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12
Q

Example of fungus

A

Candida

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13
Q

Example of virus

A

Herpes

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14
Q

Example of roundworm

A

C. Elegans

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15
Q

Example of flatworm

A

Tapeworm

Fluke

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16
Q

Example of prion

A

Mad cow disease

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17
Q

Example of proctist

A

Malaria

Leishmania

Trichomonas

Toxoplasma

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18
Q

Example of arthropods

A

Head louse

Mite

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19
Q

What three terms refer to frequency of infectious agents in humans?

A

Endemic

Epidemic

Pandemic

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20
Q

What is an endemic?

A

Persistently present in population

21
Q

What is an epidemic?

A

Increase in frequency of disease in population

22
Q

What is a pandemic?

A

Global epidemic

23
Q

What are animal reservoirs?

A

In animal reservoirs, pathogens can be maintained permanently

Infection can be trasmitted to humans

Pathogen does not normallyb cause disease in animal host

24
Q

What is an example of an infectious agent arising from animal reservoir?

A

Influenza

25
Q

What does the term epizootic mean?

A

Animal epidemic

26
Q

What does the term enzootic mean?

A

Animal endemic

27
Q

What does the term zoonotic mean?

A

Interspecies transmission of infectious agents

From animal to human

60% of human pathogens are zoonoses

Animal transmitting the disease = vector

28
Q

What is the name given to the process by which an infectious agent from humans infects animals?

A

Antroponosis

29
Q

What percentage of human pathogens are zoonoses?

A

60%

30
Q

Why do zoonotic infections happen?

A

Infection may come from:

  • natural reservoir
  • one-off accidental inter-species jump
31
Q

What is commensalism?

A

Two organisms live together and confer benefits to host/ bacteria

32
Q

What is the dictionary definition of commensalism?

A

The two organisms don’t benefit nor lose

33
Q

What is colonization?

A

Invasion and multiplication of organisms that are not commensal

34
Q

What does the term persistence/latency refer to?

A

State of infection where host cannot get rid of the pathogen

35
Q

What is the difference between latency and persistance?

A

Latency = no symptoms

Persistance = symptoms

36
Q

What does the term virulence/pathogenicity mean?

A

Ability to harm host

Determined by genetic factors of pathogen

Proteins encoded by genes = virulence factors

37
Q

What are examples of virulence factors?

A

How well pathogen spreads

How well pathogen attaches to host cells

How well pathogen replicates

How well pathogen invades

38
Q

What does the term infectivity mean?

A

Ability to spread to new host and establish infection

39
Q

What determines the infectivity of a pathogen?

A

Ability to survive outside host

Receptors pathogen bears to gain foothold into new host

40
Q

What is the incubation period of an infectious agent?

A

Time between establishment of infection and physical manifestation of the disease

41
Q

Describe the concept of cat and mouse evolution of pathogens

A

Pathogen and host constantly evolve in response to another

Exert selecton pressure

  1. Pathogen becomes virulent
  2. Host responds by mutating defences
  3. Pathogen counter-responds by overcoming defences
42
Q

The higher the population density, the easier the spread of infection

TRUE or FALSE

A

TRUE

43
Q

Does host resistance and immunity vary between individuals?

A

Yes

Hosts have varying susceptibility to pathogens depending on

Genes and relative immnunity

44
Q

Example of a host having increased immunity to a pathogen

A

Sickle cell anaemia sufferers

Resistant to malaria

45
Q

Can commensal microbes cause disease?

A

Yes

Immune impairment or alterations in host microbial flora can cause disease by commensal microbes

46
Q

What damage can arise when trying to eradicate pathogenic infection?

A

Damage may be caused by host-mediated or pathogen-mediated mechanisms

Can trigger autoimmunity

May lead to irreversible damage

47
Q

What happens if host is unable to eradicate infection?

A

Acquisition of microbe can be followed by colonozation

Colonization leads to disease

State of colonization leads to persistance

Persistent infections may reactivate and cause disease

If sufficient damage is incurred due to host-microbe interaction, death ensues

48
Q

What are the two ways by which the host can eliminate pathogen?

A

Physical defenses

Immune mechanisms

Infection, immunity and repair (52 decks)

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