External parasites Flashcards
arthropods (invertebraes)
insects and arachnids
insects
ex: flies, fleas, lice
have 6 legs
have antennae
have a head, thorax, and abdomen
arachnids
ex: ticks, mites
have 8 legs
have no antennae
have a cephalothorax and a body
lice (louse)
infestation: pediculosis
species specific
wingless
direct contact transmission
life cycle: nit (egg) —> nymph
what are the two types of lice?
mallophagia: biting/chewing
have a big head, move fast
anoplura: sucking
have narrower heads with piercing mouthparts, have large pincer claws, and can lead to anemia from sucking so much blood
diplerans
insects with wings
ex: flies, gnats, midges, mosquitos
infestation of fly larvae (maggots): myiasis or fly strike
what are examples of biting flies?
horse fly, deer fly, sand fly
hypoderma spp
“cattle grub”
eggs cluster for months then migrate to back forming nodules and breathing hole
larvae emerge and pupate on the ground
causes severe inflammatory reactions, bloat, paralysis if larvae die while along the esophagus or spinal cord
cuterebra spp
bot flies
cause benign SQ lesions called “warbles”
creates breathing hole
prone to secondary infection
they don’t feed off the host, just go through maturation stages while in host
in rodents and rabbits, opportunistic in dog and cat
gastrophilus spp
bot flies
DH: horses, large animals
“stomach bot”, “throat bot”, “nose bot”
flies lay eggs which are licked up by DH, stomach bot then incubates in mouth and swallowed which allows it to migrate to the stomach
CS: head shaking, salivation, ulcers
melophagus ovinus
flies
“sheep ked”
hairy and leathery
only dipteran that is wingless
strong legs with claws
DH: sheep and goats
blood feeders
fleas
DH: cats, dogs, other mammals
piercing/sucking mouthparts for blood feeding
act as IHs and can transmit disease (ex: Dipylidium caninum and Bartonella hensla)
ctenocephalides felis
cat flea
most common flea of dogs and cats
life cycle: egg –> larva –> pupa –> adult
can complete its life cycle in 2 weeks
lays eggs on host (up to 50 per day)
flea treatment and prevention
treat all pets in the household
treat indoor environment (treat area where pets sleep, vacuum, insecticides)
treat outdoor environment (remove organic debris, good lawn care, insecticides)
mosquitos
types: anopheles, aedes, culex
normal behavior to swarm
can cause anemia
eggs laid in water or damp soil
human infections: Malaria, West Nile, Zika, etc
animal infections: Dirofilaria immitus, EEE, WEE, West Nile, Malaria
ticks
infestation: acariasis
argasid: soft ticks
ixodes: hard ticks
blood feeders
what causes flea dermatitis?
flea saliva because it stops the blood from clotting
rhipicephalus sanguineus
brown dog tick
carries: Erlichia, Babesia, RMSF (rocky mountain spotted fever)
ixodes scapularis
deer/black-legged tick
Lyme vector
dermascentor variabilis
dog/wood tick
RMSF vector
what is the tick life cycle?
egg –> larva –> nymph –> adult
eggs laid off host
larva: 6 legs
nymph: 8 legs
nymphs feed on white-footed mice
mites
infestation: acariasis
life cycle: egg –> larva –> nymph –> adult
spend entire life cycle on host
direct contact transmission
causes mange
use skin scraping to diagnose (burrowing and non-burrowing types)
demodex spp
NF meaning they are normal flora
immune system keeps in check but if animal is stressed or is immunocompromised they will cause infection
infestation: demodicosis
CS: alopecia but not pruritic
deep skin scrape used to diagnose
sarcoptes scabiei
similar to demodex where infection only happens under stress or immunocompromised
scabies, sarcoptic mange
host specific
difficult to find on scrape (deep scrape needed)
CS: very pruritic, crusting, alopecia
transmission by direct contact
zoonotic
