Lecture 1

Question 1

definition of phoresis

Answer 1

‘to carry’ ; when two organisms are ‘traveling’ together

Question 2

commensalism

Answer 2

one member benefits while the other is unaffected

Question 3

example of commensalism

Answer 3

sea anomone provides protection against predators of the clown fish

Question 4

mutualism

Answer 4

both symbionts gain something

Question 5

example of mutualism

Answer 5

yucca plant and yucca moth; yucca moth lays its eggs in the yucca and the pollinator larvae feed exclusively on the seeds

Question 6

parasitism

Answer 6

one organism is positively affected, and the other is negatively affected

Question 7

why is parasitism difficult to define?

Answer 7

the word ‘harm’ is difficult to define

Question 8

A parasite is…

Answer 8

a living eukaryotic organism. they are not a bacteria or virus

Question 9

what are the categories of parasites?

Answer 9

1. protozoans
2. metazoans
3. endoparasites
4. ectoparasites

Question 10

3 examples of metazoans

Answer 10

1) lone star tick
2) digenean trematode
3) roundworm

Question 11

2 groups of endoparasites

Answer 11

1) protozoa
- flagellates
- amebae
- sporozoa
- ciliates
2) helminths
- nematodes
- trematoda
- cestoda

Question 12

4 examples of unicellular endoparasites

Answer 12

1) leishmania
2) plasmodium
3) trypanosoma
4) Gardia

Question 13

multicellular endoparasites

Answer 13

1) hookworm
2) tapeworm
3) tapeworm eggs
4) roundworm
5) pinworm

Question 14

hemiparasite

Answer 14

a parasitic plant that derives some, or all of its sustenance from another plant (eg. mistletoe)

Question 15

host

Answer 15

the organism in, or on, which the parasite lives

Question 16

definitive host

Answer 16

the organism in which the parasite reaches sexual maturity

Question 17

intermediate host

Answer 17

the organism in which the parasite completes part of its life cycle. usually the parasite undergoes a morphological or physiological change in this host

Question 18

reservoir host

Answer 18

alternate animal host from which the parasite can be transmitted to humans (zoonosis) or domestic animals

Question 19

accidental host

Answer 19

one that accidentally harbors a parasitic stage that is not usually parasitic in the particular species and cannot be transmitted

Question 20

vector

Answer 20

a host that plays an active role in transmission of the parasite

Question 21

infection

Answer 21

a parasite growing and multiplying within or on a host, often accompanied by an immune response

Question 22

pathogenecity

Answer 22

ability of parasite to cause disease

Question 23

virulence

Answer 23

• degree of pathogenicity

- the ability for the organism to invade, infect, grow, and cause damage despite the hosts defenses

Question 24

general steps of parasitic infections

Answer 24

1. encounter
2. entry
3. spread
4. multiplication
5. damage
6. outcome

Question 25

main modes of transmission

Answer 25

skin, respiratory, GI, urogenital symptoms, vector borne, blood transfusion, or organ transplant

Question 26

external transmission

Answer 26

passive carriage of pathogen on body of vector. no growth of pathogen during transmission

Question 27

internal transmission

Answer 27

carried within a vector. includes: harborage transmission and biologic transmission

Question 28

harborage transmission

Answer 28

pathogen does not undergo changes within vector

Question 29

biologic transmission

Answer 29

pathogen undergoes changes within vector

Question 30

definition of infectivity

Answer 30

ability of the organism to establish a discrete, focal point of infection

Question 31

definition of invasiveness

Answer 31

ability of an organism to spread to adjacent or other tissues of the host

Question 32

penetration of host’s mucous membranes or epithelium can be ___ or ____

Answer 32

active or passive

Question 33

examples of passive penetration:

Answer 33

skin lesions, insect bites, wounds

Question 34

definition of protozoans

Answer 34

unicellular endoparasites that include flagellates, amoebas, malarial organisms

Question 35

definition of helminths

Answer 35

multicellular parasitic worms that include flukes, tapeworms, and roundworms

Question 36

definition of arthropods

Answer 36

multicellular ectoparasites that include insects (lice, fleas) and arachnids (ticks, mites) that are carriers (vectors) of diseases