Parasites

Question 1

Types of parasite lifecycles

Answer 1

Direct life cycle:
Parasitic stages develop in/on individual host
e.g. cattle lung worm

Indirect life cycle:
Intermediate hosts (different species) needed for development of some stages of parasite
e.g. canine lung worm

Question 2

Types of parasite vectors

Answer 2

Mechanical vector:
Vector which mechanically spread parasite
No parasite replication occurs so mechanical vectors aren’t hosts
e.g. flies transmitting various faecal protozoal pathogens

Biological vector:
Intermediate host which is itself usually a parasite
e.g. mosquitos transmitting malaria

Question 3

Routes of parasite transmission

Answer 3

Ingestion (e.g. in food or water)
Skin penetration (e.g. hookworm larvae)
Direct animal-to-animal contact (lice)
Trans-placental
Sexual intercourse
Inhalation

Question 4

Define parasitism

Answer 4

only parasite benefits from interaction to detriment of host

Question 5

Define mutualism

Answer 5

organisms of different species both benefit from interaction

Question 6

Define commensalism

Answer 6

only 1 organism benefits from association without causing any harm to other organism

Question 7

Define symbiosis

Answer 7

close & prolonged interaction between organisms of different species

Question 8

Define hyperparasitism

Answer 8

parasites of parasites

Question 9

Define parasitoid

Answer 9

parasite that kills its host

Question 10

Define facultative parasites

Answer 10

may survive in absence of host

Question 11

Define obligate parasites

Answer 11

at some or all stages of life cycle can’t survive in absence of host

Question 12

Define endoparasites

Answer 12

live inside host

Question 13

Define ectoparasites

Answer 13

live on outer body surfaces of host

Question 14

Define definitive (final) host

Answer 14

host in which parasite sexual reproduction occurs

Question 15

Define intermediate host

Answer 15

host in which parasite asexual reproduction occurs

Question 16

Define permissive host

Answer 16

not usually used by parasite but still allows life cycle completion

Question 17

Define non-permissive host

Answer 17

host in which parasite can’t complete life cycle

Question 18

Define reservoir host

Answer 18

host in which parasite can be maintained & which is source of infection for another host that we’re interested in

Question 19

Define paratenic host

Answer 19

host not necessary for lifecycle/development, but which can act as ecological dump (reservoir) of parasite & source of infection