L2: Life Cycles Flashcards
host in which adult or sexually reproductive stages of the parasite occur
definitive (primary, principal) host
host needed for parasite development but in which the parasite does NOT become sexually mature
intermediate (secondary) host
host in which the parasite doesn’t undergo development but in which it stays alive in and is infective to other hosts
paratenic (transport) host
parasites w/ DIRECT life cycles = ?
monoxenous (parasite resides in a single species of host for its lifetime)
nematodes and protozoa
two types of infective stages in monoxenous parasites
resting stage - ingestion
active stage - ingestion, penetration of skin, direct contact
a direct life cycle includes a definitive (primary host) but no ??
intermediate host(s)
type of life cycle that requires an intermediate host
indirect
heterogenous parasites (all trematodes, most tapeworms and lots of nematodes and protozoa) have what type of life cycle
indirect life cycle
host NOT required for completion of parasite’s life cycle
Paratenic host
what is the role of a paratenic host
facilitates transmission of parasite TO the definitive host
type of parasites that serve as parasite AND vector
Arthropod ectoparasites
2 main life cycles of ectoparasites
Holometabolous(complete) metamorphosis
- fleas, dipterans
Hemimetabolous (incomplete, simple) metamorphosis
- ticks, mites, lice
Stephanurus dentatus (swine kidney worm) utilizes what host type
paratenic
what type of life cycle is characterized by
* a larval morphology that differs from the adults
* egg –> larva –> pupa –> adult
Holometabolus (complete)
what life cycle is characterized by
* larval/nymphal morphology is similar to the adults
* egg –> larva –> nymph –> adult
* egg –> nymph –> adult
Hemimetabolus (incomplete, simple)
what organism causes canine heartworm
Dirofilaria immitis
what is the mode of transmission for *Dirofilaria immitis *
Vectored by mosquitoes
what is the infective stage of Dirofilaria immitis
third-stage larva (L3) migrates through mosquito bite wound
what is the predilection site of adult Dirofilaria immitis
pulmonary arteries, right ventricle
what is the route to the predilection site for Dirofilaria immitis
venous circulation
mode of exit for Dirofilaria immitis
blood ingested by mosquito
exiting/diagnositc stage of Dirofilaria immitis
microfilaria in blood
the time between infection of a definitive host and the appearance of the stage exiting the host (eggs, cysts, etc)
Prepatent period
control through deworming
what is the definitive host for Toxoplasma gondii
felids
