Lecture 10 & 11 Arachnids: mites Flashcards
Which feature is used to divide Acarina into the four suborders that contain ticks and mites?
Spiracle location
Label these spiracle locations with the Suborder they represent.
Which suborder has no spiracles?
Astigmata has no spiracles
Label the Suborder these mites likely belong to. What other feature could you use?
Could also use spiracle location.
My latin name is ___ ____, but people usually just call me the ‘red mite of poultry’. My life cycle takes ___ days, and begins off the host when my mum lays me in ______. I prefer to come out at _____ and feed on ____. I have ____ nymphal stages and can cause ____ and ____ in my host. Most importantly though, I can transmit ___ ___ which causes spirochaetosis in chickens and other birds.
My latin name is Dermanyssus gallinae, but people usually just call me the ‘red mite of poultry’. My life cycle takes 7 days, and begins off the host when my mum lays me in crevices. I prefer to come out at night and feed on blood of my host. I have 2 nymphal stages and can cause anemia and irritation in my host. Most importantly though, I can transmit Borrelia anserina which causes spirochaetosis in chickens and other birds.
What is the most important morphological feature that allows differentiation of D. gallinae from other Mesostigmatids?
Triangular anal plate
You find hundreds of these on a wild bird brought into the clinic. What suborder and Genus are they? How did you know?
Are they host specific?
What effect would these have on the bird?
Mesostigmata - legs anterior
Ornithonyssus - narrow anal plate
Not host specific
Anaemia and reduced egg production
What is this mite?
Varroa destructor
What are the four genera of Prostigmata we are interested in?
Trombicula
Demodex
Psorbia
Cheyletiella
What suborder, family and species is this mite? Where in the skin would you find it? How many nymphal stages does it have?
Prostigmata
Demodicidae
Demodex canis
Lives in hair follicles
2 nymphal stages
What is the first diagnostic test you would perform for this patient? If you were able to diagnose D. canis, what treatment options would you recommend here?
Deep skin scrape and microscopy
Generalised demodex, so needs:
- benzoyl peroxide shampoo
- Amitraz dip (mitaban)
- high dose oral ivermectin, oral milbemycin oxime, topical moxidectin (MLs)
True or false - mites in Demodicidae are generalists.
False - each species is quite host-specific
A farmer calls you to her property in May to examine her merino sheep for lice. She has tried an OP-based dip since shearing them in January, but thinks she might have some resistance.
a) what diagnostics can you do to help her reach an answer
b) what is a likely suspect if you can’t find any evidence of Bovicola ovis, or any scabs on the sheep?
c) what drug treatment would you recommend she try? Is it the same one she has already tried?
a) part the wool to look for lice, do a skin scrape to look for mites.
b) Psorobia ovis
c) P. ovis doesnt respond to OPs. She should try a ML or amitraz drench
What genus does this mite belong to?
Cheyletiella - claws on palps are unique
Name these two Families of Astigmata. What is the main distinguishing feature?
Sarcoptidae (top) and Psoroptidae (bottom). Psoroptids legs project further.
Your patient has generalised mange, but you haven’t been able to find any mites with your deep skin scrape. Give one treatment chemical which you can start that will take care of either Demodex or Sarcoptes.
Topical moxidectin (Advantage Multi)
You perform a deep skin scrape on a patient with mange and identify this.
a) what suborder, family and species is it?
b) is it zoonotic?
c) what is one treatment you can recommend (the mange is generalised)
d) what product can you recommend for prevention for this parasite in the future?
a) Astigmata, Sarcoptidae, Sarcoptes scabiei
b) Will not complete life cycle in humans though will cause self-limiting infection
c) Can use selamectin e.g revolution
d) Can also use revolution for prevention
Which genus contains the sarcoptid mites of birds?
Knemidocoptes
What is this condition? What is the causative organism?
Scaly leg
Knemidocoptes mutans
What are the three genera of concern in the family Psoroptidae?
Otodectes
Psoroptes
Chorioptes
A cat presents to you with a history of head shaking. You detect this organism in a smear of some exudate from its ears.
a) what is the suborder, family and species most likely to be?
b) how did this cat aquire the infection?
c) what treatment options can you recommend?
a) Separate fore and hind legs - Astigmata
Found in the ear, mild clinical history, projecting rear legs - Psoroptidae, Otodectes cynotis
b) Contact with another infected cat, likely as a kitten nursing
c) topical moxidectin/imidacloprid (advantage), selamectin (revolution)
You are called to a farm in WA to investigate production losses in the sheep. You examine a sheep with this lesion. Do you a) part the wool and look for lice, b) make a skin scrape to look for mites or c) something different?
c) These scabs are typical of the sheep scab mite, Psoroptes ovis. You would try and get a sample from beneath the scab for the microscope.
You have isolated this parasite from the sheep in the previous flashcard. What is the significance of this finding a) for the sheep and b) for biosecurity?
Sheep: Causes irritation, emaciation. Treat with MLs.
Biosecurity: this is an exotic parasite. Must notify authorities.
(Astigmata > Psoroptidae > Psoroptes ovis)
What is the most likely Suborder, Family and species cause of this ? What is the treatment?
Astigmata > Psoroptidae > Psoroptes cuniculi
Avermectins
What feature do you use to distinguish the genera Chorioptes and Psoroptes? Which is which here?
Is Chorioptes bovis host specific?
No - causes chorioptic mange (= barn itch) in sheep, cattle, goats and horses
