Mites As Parasites

Question 1

Mite pathway to inflammation

Answer 1

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

Question 2

Host resp to mange mites

Answer 2

Prod immediate inflam resp
Adaptive imm resp bia APCs
Innate imm eg eosins in stratum corneum
Protective imm takes time to dev

Question 3

Adaptation to surf living

Answer 3

Large mites
Stout bodies
Long legs

Question 4

Adaptation to living in epidermis

Answer 4

Small mites
Flattened round bodies
Short legs

Question 5

Adaptation to living within follicle

Answer 5

Small Elongated body

Very stubby legs

Question 6

Adaptation to free living

Answer 6

Large

Very long legs

Question 7

Diagnosis of infestations in diff areas

Answer 7

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

Question 8

Mange diagnosis

Answer 8

Clinical signs
Lesion distribution
Mite ID on skin scrapes or adhesive tape

Question 9

Mange mite lifecycle

Answer 9

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

Question 10

Psoroptes ovis lifecycle

Answer 10

Same as gen mange mite lifecycle

Question 11

Psoroptes ovis

Answer 11

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

Question 12

Sheep scab as an ND

Answer 12

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

Question 13

Sheep scab symptom progression

Answer 13

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

Question 14

Psoroptes cuniculi

Rabbit ear canker

Answer 14

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

Question 15

Chorioptes

Answer 15

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

Question 16

Goat chorioptic mange

Answer 16

Dry crusting scabs on lower limbs
Severe exudative dermatitis affecting whole body of individuals with matted overlying hair
Severe pruritis

Question 17

Sheep chorioptic mange

Answer 17

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

Question 18

Cattle and horse chorioptic mange

Answer 18

Lesions tend to be localised
Tail head of cattle
Pasterns of horses (greasy heel)

Question 19

Otodectes cynotis - ear mites

Answer 19

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

Question 20

Sarcoptes scabiei - sarcoptic mange

Answer 20

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

Question 21

Sarcoptic mange in pigs

Answer 21

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

Question 22

Sarcoptic mange in dogs and foxes

Answer 22

Intense pruritus
Lesions begin on ears and spread over the body
Similar to dis in other species

Question 23

Sarcoptes scabiei var ovis

Answer 23

Problem in S EU - present in UK???
Burrowin mites
Intense pruritus and thick crust formation
Affects face, groin, limbs and axillae esp

Question 24

Psorobia ovis

Answer 24

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

Question 25

Notedres cati - notedric mange in cats

Answer 25

``` Rare in Uk Key in EU Contagious Zoonotic Intensely pruritic ```

Question 26

Trixacarus caviae (guinea pig mite)

Answer 26

Burrowing (similar to sarcoptes) Transmission fron mother to offspring Inflam severe pruritis scaling self trauma and sometimes death

Question 27

Knemidocoptes pilae - depluming itch mites and scaly leg mites of birds

Answer 27

Scaly feet and wings

Question 28

Demodex - demodectic mange

Answer 28

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

Question 29

Cattle and sheep demodectic mange

Answer 29

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

Question 30

Cheyletiella | VECTOR!!!

Answer 30

``` 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 ```

Question 31

Mycoptes and myobia - rodent fur mites

Answer 31

Live on and amongst hair not on the skin | Low grade pruritus and alopecia in severe infestations

Question 32

Thrombiculids- harvest mites

Answer 32

``` 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 ```

Question 33

``` Dermanyssus gallinae (poultry red mite) VECTOR!!! ```

Answer 33

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

Question 34

Ornithonyssus sylviarum - northern fowl mite | VECTOR!!!

Answer 34

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

Question 35

Forage mites (non parasitic)

Answer 35

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

Question 36

House dust and storage mites (non parasitic)

Answer 36

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

Question 37

Id of parasitic v non parasitic

Answer 37

Diff mouthparts. Parasitic have feeding mouthparts and non parasitic dont