L2: Life Cycles

Question 1

host in which adult or sexually reproductive stages of the parasite occur

Answer 1

definitive (primary, principal) host

Question 2

host needed for parasite development but in which the parasite does NOT become sexually mature

Answer 2

intermediate (secondary) host

Question 3

host in which the parasite doesn’t undergo development but in which it stays alive in and is infective to other hosts

Answer 3

paratenic (transport) host

Question 4

parasites w/ DIRECT life cycles = ?

Answer 4

monoxenous (parasite resides in a single species of host for its lifetime)
nematodes and protozoa

Question 5

two types of infective stages in monoxenous parasites

Answer 5

resting stage - ingestion
active stage - ingestion, penetration of skin, direct contact

Question 6

a direct life cycle includes a definitive (primary host) but no ??

Answer 6

intermediate host(s)

Question 7

type of life cycle that requires an intermediate host

Answer 7

indirect

Question 8

heterogenous parasites (all trematodes, most tapeworms and lots of nematodes and protozoa) have what type of life cycle

Answer 8

indirect life cycle

Question 9

host NOT required for completion of parasite’s life cycle

Answer 9

Paratenic host

Question 10

what is the role of a paratenic host

Answer 10

facilitates transmission of parasite TO the definitive host

Question 11

type of parasites that serve as parasite AND vector

Answer 11

Arthropod ectoparasites

Question 12

2 main life cycles of ectoparasites

Answer 12

Holometabolous(complete) metamorphosis
- fleas, dipterans
Hemimetabolous (incomplete, simple) metamorphosis
- ticks, mites, lice

Question 13

Stephanurus dentatus (swine kidney worm) utilizes what host type

Answer 13

paratenic

Question 14

what type of life cycle is characterized by
* a larval morphology that differs from the adults
* egg –> larva –> pupa –> adult

Answer 14

Holometabolus (complete)

Question 15

what life cycle is characterized by
* larval/nymphal morphology is similar to the adults
* egg –> larva –> nymph –> adult
* egg –> nymph –> adult

Answer 15

Hemimetabolus (incomplete, simple)

Question 16

what organism causes canine heartworm

Answer 16

Dirofilaria immitis

Question 17

what is the mode of transmission for *Dirofilaria immitis *

Answer 17

Vectored by mosquitoes

Question 18

what is the infective stage of Dirofilaria immitis

Answer 18

third-stage larva (L3) migrates through mosquito bite wound

Question 19

what is the predilection site of adult Dirofilaria immitis

Answer 19

pulmonary arteries, right ventricle

Question 20

what is the route to the predilection site for Dirofilaria immitis

Answer 20

venous circulation

Question 21

mode of exit for Dirofilaria immitis

Answer 21

blood ingested by mosquito

Question 22

exiting/diagnositc stage of Dirofilaria immitis

Answer 22

microfilaria in blood

Question 23

the time between infection of a definitive host and the appearance of the stage exiting the host (eggs, cysts, etc)

Answer 23

Prepatent period

control through deworming

Question 24

what is the definitive host for Toxoplasma gondii

Answer 24

felids

Question 25

what are the intermediate hosts for Toxoplasma gondii

Answer 25

mammals + birds

Question 26

what are the definitive hosts for Schistosoma japonicum

Answer 26

• rodents
• carnivora
• ungulates
• primates
• other mammals

Question 27

what is the intermediate host for Shistosoma japonicum

Answer 27

snails in genus Oncomelania

Question 28

what are the definitive hosts for Plasmodium reichenowi (malaria)

malaria

Answer 28

mosquitos in genus Anopheles

Question 29

what is the intermediate host for Plasmodium reichenowi (malaria)

Answer 29

chimpanzees

Question 30

what is the difference between Holometamorphosis and Hemimetabolous life cycles in ectoparasites

Answer 30

Holometamorphosis - larval morphology differs from adult
Hemimetabolous - larval/nymphal morphology is similar to that of the adult

Question 31

parasites with what type of lifecyle can have different specificities during life cycle stages

Answer 31

Indirect lifecyle
- trematodes, tapeworms, parasitic nematodes+protozoa