Mites As Parasites Flashcards
Mite pathway to inflammation
Mechanical abrasion and allergen deposition cause skin barrier disruption
Activates 1o rec cause release of inflam med IL6&8 and TNF trigger pro inflam cascade cause selectin and integrin expr
Cause leukocyte extravasation activating local DCs bridging innate to adaptive resp and causing loxal skin inflam
DC cell act TH2 resp which causes further disruption
Host resp to mange mites
Prod immediate inflam resp
Adaptive imm resp bia APCs
Innate imm eg eosins in stratum corneum
Protective imm takes time to dev
Adaptation to surf living
Large mites
Stout bodies
Long legs
Adaptation to living in epidermis
Small mites
Flattened round bodies
Short legs
Adaptation to living within follicle
Small Elongated body
Very stubby legs
Adaptation to free living
Large
Very long legs
Diagnosis of infestations in diff areas
Surf: tape strip or superficial skin scrape
Burrowing: deep skin scrap
Hair follicle: squeeze pustules onto slide
Specific sites: direct observation
Other diagnostic tests: haematology, chemistry, serology
Mange diagnosis
Clinical signs
Lesion distribution
Mite ID on skin scrapes or adhesive tape
Mange mite lifecycle
Eggs laid on skin (or other niche) and larvae dev in approx 3d
Larvae feed for 3-7d then moult
Nymphs emerge and change into males and pubescent females after 5d
About 3-4wk to complete
All dev stages on host and transmission by close contact (or rarely short survival period on fomites)
Susceptible to dessication so dont survive long off host
rarely able to infect new host of survived off host
Psoroptes ovis lifecycle
Same as gen mange mite lifecycle
Psoroptes ovis
Sheep scab
Cause of intense pruritus and after 6 wk wool loss and skin damage timescale dep on strain of mite, time of hr, length of wool, etc
Important animal welfare concern
Important cause of production loss
ND in scotland
Large money spent on inneffective disease control
Sheep scab as an ND
Legal obligation to notify DVM in scotland
Voluntary movement restrictions until treated slaughtered or negatively diagnosed
Failure to act can lead to compulsory movement restrictions and req to treat or slaughter affected animal in absence of negative diagnosis
Persistent offence can lead to prosecution
Powers to act when sheep scab discovered at market and deal with stray sheep
Sheep scab symptom progression
6wk post: clear serous exudate, crust formation which adheres to wool fibres and start to lift off skin
10wk post: wool loss area, skin with no wool is dry and hardened and hyperkeratatic, margin area exudative
3mnth post: epiderm split into layers and mite pop between each layer
Exudate is pro rich and so become quickly hyperprotonaemic so lose weight
Psoroptes cuniculi
Rabbit ear canker
Diff to distinguish from ovis
Localise ears and prolif to severe mange
Scales cont parasite, mite eggs, skin cells and blood can block auditory canal
Untreated can spread to whole body causing pruritus hair loss and debilitation
Chorioptes
Surf mites with bell shaped suckers on short pedical
Hypersens reaction causing exudative dermatitis
Variable pruritis level along with scaling hair loss and crusting
Host specific variants
Goat chorioptic mange
Dry crusting scabs on lower limbs
Severe exudative dermatitis affecting whole body of individuals with matted overlying hair
Severe pruritis
Sheep chorioptic mange
Exudative dermatitis of wool less areas of lower limbs and poll (and scrotum of rams which reduces ram breeding soundness if over a third of the scrotum is affected)
Scab covered erythematous lesions which progress to exudative haemmorrhagic fissured lesions
Re emergence coincide with removal of compulsory dipping fo sheep scab? As it is not controlled by systemic endecticides
Cattle and horse chorioptic mange
Lesions tend to be localised
Tail head of cattle
Pasterns of horses (greasy heel)
Otodectes cynotis - ear mites
Bell shaped suckers on short pedicel
Dogs and cats
Most animals infested with commensals
Hypersens to allergens produced during feeding
Signs range from asympt to severe
Young animals acquire from dam during suckling
Sarcoptes scabiei - sarcoptic mange
Burrowing mite
Esp in foxes dogs and pigs (host spec variants)
Highly contag and easy to spread
Temporarily zoonotic
Hypersens causes intense pruritus and severe inflam and scaling crusting and hair loss
Cause scabies in humans
Sarcoptic mange in pigs
Burrow within epidermis
Now rare due to control measures
Introduced with bought animals and spread by close contact
Cause papular eruptions, erythema, pruritus and hair loss leading to skin thickening and crusting
Loss of appetite and weight loss
Lesions start around the edges of ears and spread over the body
Sarcoptic mange in dogs and foxes
Intense pruritus
Lesions begin on ears and spread over the body
Similar to dis in other species
Sarcoptes scabiei var ovis
Problem in S EU - present in UK???
Burrowin mites
Intense pruritus and thick crust formation
Affects face, groin, limbs and axillae esp
Psorobia ovis
Non burrowing
Deep in superficial epid of sides, flanks and thighs of fine wooled breeds
Not in UK
Mild prurirtus, tuft of wool displacement, self excoriation
Gives dry scaly and hyperkertotic skin (fleece bound together by scurf)
Devalues fine wool in Aus
Notedres cati - notedric mange in cats
Rare in Uk Key in EU Contagious Zoonotic Intensely pruritic
Trixacarus caviae (guinea pig mite)
Burrowing (similar to sarcoptes)
Transmission fron mother to offspring
Inflam severe pruritis scaling self trauma and sometimes death
Knemidocoptes pilae - depluming itch mites and scaly leg mites of birds
Scaly feet and wings
Demodex - demodectic mange
Commensals on most mammals (hist spec variants)
Transferred from dam to offspring during suckling but otherwise not contagious (except d. Gatoi)
Not usually pruritic (except d gatoi)
Affects face limbs eyelids and back
Can cause severe dis in immunocompromised animals
Cattle and sheep demodectic mange
Usually clin insignificant occassionally obvious
Aesthetic and hide dam in production from follicular infection
Dam to face of calf transmission in suckling
Non pruritic
Can cause hypertrophy of the sebaceous glands
Cheyletiella
VECTOR!!!
Common in dogs and rabbits Highly contag in rabbit colonies Walking dandruff Variable pruritus Myxomatosis transmission Zoonotic: can penetrate clothing after only short contact period with an infected animal, can cause persistent irritation and pruritus, early erythrmatous lesions can progress to vesicular and pustular eruption and dev persistent rash, resolve spontaneously once treated in the natural host
Mycoptes and myobia - rodent fur mites
Live on and amongst hair not on the skin
Low grade pruritus and alopecia in severe infestations
Thrombiculids- harvest mites
Parasitic as larval stage Nymph and adult live on decaying vegetation Common in dogs and cats Seasonal summer occurance High prevalence in SE Scotland Severe irritation and pruritus
Dermanyssus gallinae (poultry red mite) VECTOR!!!
Most time spent off host in dark cracks and crevices in housing or in nests
Adults and nymphs ‘attack’ birds at night to feed on blood
Rapid population growth
can cause massive infestations
Cause pruritus and inflam, anaemia, red prod, death
Adults can survive long periods in empty sheds
Transmit borreliosis and spirochaetosis
Ornithonyssus sylviarum - northern fowl mite
VECTOR!!!
Entire lifecycle spent on host
Red productivity due to irritation and anaemia
Transmission of fowl pox and newcastle dis
Some bite and feed on humans
Forage mites (non parasitic)
Climb onto face legs or flanks of sheep providing dissem method
Occassionally cause hypersens/pruritus
Hair or wool loss over affected areas
Control is impossible
Often seen in faeces when performing worm egg counts
House dust and storage mites (non parasitic)
Storage mites found on hay and grain
Cause asthma in humans following antigen inhal in faeces or on mite body
Also common cause of atopic dermatitis
Id of parasitic v non parasitic
Diff mouthparts. Parasitic have feeding mouthparts and non parasitic dont
