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ECOL 182R > Lecture 12: Parasites and Disease > Flashcards

Lecture 12: Parasites and Disease Flashcards

1
Q

Behavior Modification

A

increases its transmission by changing the behavior of its host
(ie - parasite infects snail; snail eaten by birds, birds poop, snails eat poop.

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2
Q

Estimates suggest that as many as ____________ are parasites!

A

-half of all species

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3
Q

Why are there so many parasites?

A

1) most free living species have parasites associated with them
2) Most parasites are specialists (they attack few or maybe just one species)

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4
Q

Evidence of Specialization

A

(Each) Species of parasite = one species of host

and Coevolution

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5
Q

Coevolution

A
  • Genetic change in one species in response to change in another.
  • Coevolution occurs in species that are closely interacting, (e.g., mutualists, parasites & hosts, pollinators and plants)
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6
Q

How do we detect coevolution of parasite and host?

A

Quantitative approach looking for Co-speciation

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7
Q

What is the Quantitative approach?

A

Quantitative approach: Evaluate branch patterns of both parasite and host phylogenies in parallel

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8
Q

Co-speciation

A

A kind of coevolution that occurs when one species (host) speciates and the other one (parasite) does too.

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9
Q

Most parasites must:

A

Most parasites must:

1) Find “SAFE” host versus a hostile environment
2) ESTABLISH on/in host (e.g., cross into skin, gut wall, etc.)
3) EVADE host immune system, or if ectoparasite, behavioral defense (grooming, swatting)
4) grow and REPRODUCE in host
5) DISPERSE from and find new host

*Adaptations for one species of host unlikely to be effective for another

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10
Q

ectoparasite

A

lives outside host (flea)

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11
Q

Parasites are grouped by

A

-size

1) Microparasites: unicellular (e.g., viruses, bacteria, protists, and single-celled fungi)
2) Macroparasites: multicellular (e.g., arthropods, nematodes, flatworms, and multicellular fungi)

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12
Q

Size influences…

A

-the way the host is used…

  • Microparasites generally infect cells,
  • Macroparasites are usually external or in the gut
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13
Q

Microparasites generally…

A

-infect cells

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14
Q

Macroparasites are usually…

A

-external or in the gut

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15
Q

Are parasites unicellular or multicellular?

A
  • Microparasites: unicellular (e.g., viruses, bacteria, protists, and single-celled fungi)
  • Macroparasites: multicellular (e.g., arthropods, nematodes, flatworms, and multicellular fungi)
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16
Q

How are parasites transmitted?

A

Directly or indirectly

17
Q

Direct (parasite) transmission

A

-from one host to another of the same species

18
Q

Indirect (parasite) transmission

A

-transmission via another species

19
Q

Types of direct (parasite) transmission

A

vertical or horizontal

20
Q

What is vertical transmission?

A

Vertical transmission is transmission from parent to offspring in early development, generally from mother to offspring.

  • through infected gametes (most often eggs) - through birth process (mother –> offspring)
21
Q

what is horizontal transmission?

A

-transfer via contact with infected individuals or contaminated products

22
Q

Strictly vertically-transmitted parasites (i.e., no horizontal transmission) are…

A

unusual

23
Q

Why are strictly vertically-transmitted parasites (i.e., no horizontal transmission) unusual?

A
  • Dependent on their hosts, often evolve into mutualists, rarely make their hosts sick.
  • But some manipulate the reproduction of their hosts to increase their own transmission
24
Q

How is it possible for a parasite to cause a male to turn into a female?

A

-because they have a haplodiploid genetic system

Example: Wolbachia bacteria
-Wolbachia bacteria pass on from one generation to the next via infected eggs (i.e., from mother)
• Takes over reproductive system so host only produces females

25
Q

haplodiploid

A

combines both in a single animal species!

26
Q

Property of Wolbachia has been used in mosquitoes…

A

to prevent the transmission of dengue fever

27
Q

Parthenogenetic Infected Species

A

no males or ability to reproduce sexually

28
Q

Parthenogenesis

A

the production of an organism from an unfertilized egg

29
Q

When they’re both vertically and horizontally transmitted, parasites often …

A

-make hosts sick

• ie- HIV, rubella, syphilis, hepatitis B…

30
Q

When parasite is transmitted from one host to the other host via another species. (indirect transmission/only horizontal) The other species may be _____ or ________ hosts.

A
  • vectors

- intermediate hosts.

31
Q

Vectors

A

ectoparasites of the host; serve as a hypodermic of pathogen

ie- mosquito

32
Q

Intermediate hosts may _________ to definitive hosts (e.g., Schistosoma), or may …

A
  • live in proximity

- be prey of the final hosts

33
Q

Explain cycle of Schistomosa

A

1) Parasite eggs shed in human waste, gets into water
2) Eggs hatch, infect snails
3) Snails shed swimming stage
4) Burrow into human skin, infect organs, reproduce

34
Q

For direct, horizontally-transmitted parasites… exit routes may be …

A

feces, body fluids, lesions, etc.

35
Q

Transmission is dependent on:

For direct, horizontally-transmitted parasites

A
  • DENSITY of hosts

- FREQUENCY of encounters between infected and uninfected individuals

36
Q

For indirect parasites…

Transmission depends on:

A
  • the INTERACTION of the two hosts (or more)

- aspects of the HABITAT (temperature, moisture, etc.) if any free-living stages

37
Q

For indirect parasites…

Transmission depends on:

A
  • the INTERACTION of the two hosts (or more)

- aspects of the HABITAT (temperature, moisture, etc.) if any free-living stages

38
Q

Virulence

A
  • Severity of disease
  • Harmfulness of effects
  • How sick the host gets
39
Q

Virulence is generally related to…

A

-the speed at which host is infected (i.e., converted to parasites)

ECOL 182R (19 decks)

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