PA3: Mites Flashcards
(24 cards)
How do mites cause inflammation?
They abrade the skin & deposit allergens via saliva/faecal packages.
What is the adaptive immune response to parasites?
APC, Langerhans cells, DC, monocytes
What is the innate immune response to parasites?
Keratinocytes, eosinophils, basophils, neutrophils, mast cells.
What are the different ecological of mites?
On the epidermis
Within the epidermis
In hair follicle
Examples of mites found on the epidermis
Psoroptes, Chorioptes, Otodectes, Cheyletiella, Demodex, Trombiculids, Dermanyssus
Examples of mites found within the epidermis (burrowing mites)
Sarcoptes, Notedres, Knemidocoptes
Example of mites found in hair follicle
Demodex
What are the diagnostic methods used for different types of mites?
Tape stripping/superficial skin scraping for surface living mites
Deep skin scraping for burrowing mites
Hair follicle mites by squeezing pustules of hair follicles onto slide.
Haematology/biochemistry/serology
Characteristics of Psoroptes ovis (sheep scab)
Obligate parasites
Lifecycle of ~20 days
Clinical signs like intense pruritus, wool loss, skin damage, weight loss.
Notifiable in Scotland
Characteristics of Psoroptes cuniculi (rabbit ear canker mite)
Found in ear (site specific)
Clinical signs: can block ear canal + if spreads to whole body pruritus, hair loss & debilitation.
Characteristics of Chorioptes spp.
Surface-living mites
Cause exudative dermatitis, pruritus, scaling, crusting & hair loss.
Host specific variants (found in goats, sheep, cattle & horses)
Characteristics of Otodectes cynotis (ear mites of dogs & cats)
Usually commensal but some animals have hypersensitivity reactions
Young animals get them while suckling dams
Characteristics of sarcoptes scabeii (sarcoptic mite)
Burrowing mite
Important in dogs, foxes & pigs
Very contagious
Causes sarcoptic mange, intense pruritus, inflammation, scabing, crusting & hair loss
Sheep version is sacrcoptes scabeii var ovis
Characteristics of Notodres cati.
Found in cats
Burrowing
Causes intense pruritus
Zoonotic
Characteristics of Trixacarus caviae (guinea pig mite)
Burrowing mite similar to sarcoptic mites
In guinea pigs
Vertical transmission
Causes severe pruritus & inflammation, scaling & death.
Characteristics of Knemidocoptes pilae
Found in birds
Causes depluming, scaly face, feet & wings
Characteristics of Demodex spp.
Found in hair shaft
Vertical transmission during suckling
Most contagious & pruritic is D. gatoi in cats
Causes pustule formation
Characteristics of Cheyletiella spp.
Common in dogs & rabbits
Causes pruritus & seborrhoea.
Vector for myxomatosis in rabbits
Zoonotic
Characteristics of Mycoptes & Myobia spp.
Rodent fur mites
Live in the fur instead of on the epidermis
Causes pruritus & alopecia if severe
Characteristics of trombiculids (harvest mites)
Temporary parasites: only larval stage is parasitic
Normal host is small rodents, but larval stage is commonly found in dogs/cats
Prevalent at end of summer
Found in SE Scotland
Characteristics of Dermanyssus gallinae (poultry red mite)
Temporary parasites: adults & nymphs attack birds at night for a blood meal
Live in dark areas
Rapid pop. growth
Causes pruritus & restlessness
Can attack humans if adult mites are hungry
Vectors for transmission of borreliosis & spirochaetosis.
Characteristics of Ornithonyssus sylviarum (northern fowl mite)
Obligate parasite
Causes irritation, anaemia & decreased production
Vectors for transmission of fowl pox & Newcastle disease
Zoonotic
What are the pathogenic but non-parasitic mites?
Forage mites common in sheep
House dust & storage mites that cause atopic dermatitis in dogs/cats + asthma in humans
How do the pathogenic but non-parasitic mites cause disease?
Through hypersensitivity reactions
