Arachnida - Acarina Flashcards
Difference from ticks?
Mouth parts, hypostome lacks rows of teeth most are free living and non parasitic
Lifecycle
egg -> larva (6legs) -> nymphs (proto-, deuto-, triti-), -> adults
Types of parasite
can be intermittent or permanent
Where on host?
on skin, ears or respiratory system
Mite effect on hosts
blood loss, irritation, hair loss, vector of disease
Suborder mesostigmata
gamasid mites -> spiracles between coxae
suborder prostigmata
trombiculid mites -> spiracles on capitulum (or absent)
Suborder astigmata
mange mites-> no spiracles (respiration through body wall)
Which suborder?
mesostigmata
legs at anterior end
Which suborder?
Prostigmata
feather like setae
Which suborder?
Astigmata
front legs separated from back
The red might of poulty
Dermanyssus gallinae
Dermanyssus gallinae features
trangular anal plate
parasite of birds and mammals
nocturnal
blood feeders
Lifecycle of Dermanyssus gallinae
eggs- > larvae-> 2 nymphs -> adults
7 day lifecycle
Dermanyssus gallinae effect on host
anaemia
irritation
transmit Borrelia anserina (spirochaetosis)
What is this fowl mite?
Ornithonyssus spp
O. bursa or O. sylviarum
Features of Ornithonyssus spp
common on wild birds
found in birds nests
referred to as “starling lice”
feed on birds in nest
blood feeders (to complete lifecycle)
not host specific
Honey bee mite
Varroa destructor
Varroa destructor impact
causes varroosis
sucks hemolymph
Contributing factor to colony colapse disorder
Varroa destructor lifecycle
Enter bee hive on the back of a bee -> jump off and infect bee pupa -> sucks haemolymph and lays eggs -> the hatch and will attach onto other bees
Prostigmata genus
Trombicula
Demodex
Psorbia
Cheyletiella
Which stage of the Trombicula is parasitic?
larvae
What does Trombicula sarcina cause?
“black soil itch” in Qld
-extreme itching and inflammation
reddish larvae are in papules on the skin
What is this?
Demodex canis
Features of demodex canis
-veriform (worm like)
Localisation: hair follicles, feed on cytoplasm
Demodex canis lifecycle
egg, larva, 2 nymph stages, adult (all stages in hair follicle)
Transmissino of demodex canis
contact during suckling
Adult or nymph?
adult - developed hypostome and legs
Demodectic mange features
all dogs infected
- only immunocompromised develop disease (CMI deficiency)
- mostly puppies 6-10 month old
- normally around eyes, ears and muzzle
- secondary straph albus infection
- hair follicle infection leads to hair loss & hyperkeratosis
Demodectic mange disease can be
- localised or generalised
- squamous or pastular (secondary infection) - check for underlying disease
How to diagnose demodex canis
deep skin scraping
treatment of demodex canis
Localised - spontaneous resolution
- rotenone-based insecticide ointment
Generalised - extended, aggressive therapy
- benzoyl peroxide shampoo
- Amitraz dip
- high dose of ivermectin, oral milbemycin oxime, topical moxidectin, injectable doramectin
Other demodex species (host specific)
Pig - D. phylloides (lesions on head)
Cattle - D.bovis (damage hide)
Cat - C. cati (alopecia, crusts, scaling on face, neck and eyelids)
What is this?
Psorbia ovis
Psorbia ovis features
tiny
lives in superficial layers of dermis
Transmission of Psorbia ovis
contact - shearing/suckling
Seasonal occurance of psorbia ovis
most abundant in winter
Psorbia ovis effect on host
hypersensitivity causes irritation -> rubbing -> pulled wool
-spreads slowly through mob (as opposed to bovicola ovis which speads quickly)
Diagnosis of Psorbia ovis
skin scraping
Treatment of Psorbia ovis
none
amitraz
Macrocytic lactone drench
OP’s
ivermectin; won’t eliminate mites
what genus is this?
Cheyletiella (claw on palp)
Cheyletiella effect on host
mild mange
often on head
“walking dandruff”
can be zoonotic
Which family of astigmata?
Psoroptidae
Which family of astigmata?
sarcoptidae (rear legs short)
burrow in upper layers of skin
What is this?
sarcoptes scabiei
Features of sarcoptes scabiei
triangular scales on dorsum
wide host range
very serious
takes a long time to get rid of
is highly contagious
animals don’t have to be immunocompromised
sarcobtes scabiei lifecycle
in superficial layers of skin
lay eggs in tunnel
larva and 2 nymphal stages
10-17 days total
mites survive a few days off host
transmitted by contact
Pathogenesis of sarcopes scabiei
Burrowing causes irritation
intense pruritus (itching)
hyperkeratosis
alopecia
lesions start on face and then extend over body
seconday infection, pustules -> self inflicted trauma
hypersensitivity
Canine specific sarcoptes mange
diagnosis
treatment
- deep skin scraping
- identify with response to treatment
selemectin, topical moxidectin/imidacloprid
Control of sarcoptes scabiei
routine fipronil, topical moxidectin, selamectin
What is this mite?
Notoedres cati - mostly on cats and rabbits
sarcoptid mites of birds
Knemidocotes
Knemidocoptes species
gallinae - in feathers, depluming mite of poultry
mutans - on legs of chickens (scaley leg)
pili - on beak and leg of psittacines
Genera of Psoroptidae
Otodectes - ear mite of cat and dog
Psoroptes - mite of ruminant, horse (joint pedicels)
Chorioptes - mite of ruminants, horses (simple pedicels)
Features of otodectes cynotis
- common in ears of cat and dog (also in rabbit and fox)
- causes scabs in external ear canal
- hosts shake head
- transmission by contact (normally during suckling)
Diagnosis of otodectes
examine under microscope (swab and put on slide)
Treatment of otodectes cynotis
topical moxidectin/imidacloprid and selamectin
Sheep mite
Psoroptes ovis
Features of psoroptes ovis
sheep scab mite (live under scabs)
feed on tissues, cause serous exudate
9-10 day lifecycle
Starts on shoulders and back and then spreads
can occur in ears, inguinal folds, interdigital spaces
most abundant in cool weather
- can have amaciation and high mortality
- eradicated from Aus
Ear mite
Psoroptes cuniculi
Hosts of Psoroptes cuniculi
rabbit, horse, goat, alpaca?
Psoroptes cuniculi causes..
ear mange
ittitaion, shacking of head, self mutilation
mite can eat ears off
Treatment of psoroptes cuniculi
Avermectins (don’t remove crusts) or animal can die from shock (painful)
Chorioptes bovis features
causes choriioptic mange
in cattle, sheep, goats and horses
-occurs on legs and belly
refered to as barn itch
cause scrotal mange in rams
