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Veterinary Medicine Year 2 > ENI - Mites > Flashcards

ENI - Mites Flashcards

1
Q

What are the differences between insects and arachnids?

A
  • Insects have 3 pairs of legs, arachnids have 4 (except larval stage of tick, has 3)
  • Arachnids have hemimetabolic life cycles, lice have hemimetabolic, other insects have homometabolic
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2
Q

What is the scutum?

A

Hard shield or plate on dorsum of “hard” or Ixodid tick

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3
Q

What is the hypostome?

A
  • Mouthpart of tick, used to anchor tick in position while feeding
  • Also serves to form gutter for blood and saliva
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4
Q

How can mites and ticks be distinguished from one another?

A

Mites do not have hypostome or scutum

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5
Q

How can the presence of mites be confirmed?

A
  • Hair pluck
  • Skin scrape
  • Coat brush
  • Serological test
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6
Q

What are the 2 types of mites?

A
  • Burrowing

- Surface

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7
Q

List the important species of burrowing mites

A
  • Sarcoptes
  • Trixacarus
  • Notoedres
  • Knemidocoptes
  • Demodex
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8
Q

Describe the apperance of burrowing mites

A
  • Rounder

- Short legs

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9
Q

Describe the appearance of Demodex

A
  • Long, thin

- Short legs in one area near head (look a little like rings)

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10
Q

Describe the life cycle of mites

A
  • Eggs laid by female
  • Larvae hatch
  • Become nymphal stage
  • Develop into adults
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11
Q

Describe Sarcoptes scabei

A
  • One species, find host-adapted strains in most mammals
  • Highly contagious, zoonotic
  • Entire life cycle on host
  • Intense pruritus caused by hypersensitivity to mite faecal material
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12
Q

How is infestation with Sarcoptes scabei diagnosed?

A

Deep skin scraping in 12 or more affected areas

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13
Q

Describe Trixicarus caviae

A
  • Guinea pigs
  • Burrowing
  • Intense pruritus, alopecia, dermaitis
  • May show secondary infectionand stres
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14
Q

How is infestation with Trixicarus caviae diagnosed?

A

Examination of hair shafts or skin scrapings to identify mite

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15
Q

Describe Notoedres cati

A
  • Mainly in cats
  • Burrows into skin
  • May produce pruritus, alopecia and dermatitis
  • Especially on head and around ears
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16
Q

Describe Knemidocoptes

A
  • Scaly face, scaly foot, tassel foot in birds
  • Highly contagious
  • Inflammation and exudate that dries
  • Appears similar to papilloma or pox virus
  • Intense hypersensitivity reaction
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17
Q

Describe the appearance of infestation with Knemidocoptes

A
  • Inflammation
  • Exudate that dries
  • Hyperkeratosis lameness, deformities
  • Rock hard, crumbly lesions
  • Pruritus, scratching
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18
Q

Describe Demodex

A
  • Highly specialised
  • Lives in hair follicles and sebaceous glands
  • Host specific
  • Infest meibomian glands as commensals
  • Disease mainly in dogs
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19
Q

Where does the life cycle of Demodex take place?

A

Entire life cycle in one sebaceous gland/hair follicle

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20
Q

Describe Demodex in dogs

A
  • Very common
  • Often underlying disease
  • Often secondary to Staphylococcal pyoderma
  • Localised or generalised
  • Chronic and difficult to treat
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21
Q

Describe localised demodicosis

A

Commonly on face and forelegs of young animals

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22
Q

Describe generalised demodicosis

A

More severe, widespread from onset, often underlying disease

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23
Q

How is infestation with Demodex diagnosed?

A

Hair pluck and deep skin scrape

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24
Q

What are the important families of surface mites?

A
  • Psoroptidae
  • Cheyetiellidae
  • Trombiculidae
  • Dermanyssidae
  • Macronyssidae
  • Listrophoridae
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25
Q

What are the important genera of Psoroptidae?

A
  • Psoroptes
  • Chorioptes
  • Otodectes
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26
Q

What is the important genera of Cheyletiellidae/

A

Cheyletiella

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27
Q

What is the important genera of Trombiculidae?

A

Trombicula

28
Q

What is the important genera of Dermanyssidae?

A

Dermanyssus

29
Q

What is the important genera of Macronyssidae?

A

Ornithonyssus

30
Q

What are the important genera of Listrophoridae?

A
  • Chirodiscoides

- Listrophorus

31
Q

What are the only free living mites?

A

Trombicula - only parasitic in larval stages, jump on, bite, then off again

32
Q

What is infestation by Sarcoptes scabei known as?

A

Mange

33
Q

What is infestation by Psoroptes ovis known as?

A

Sheep scab

34
Q

Name the important strains of Psoroptes and their host species

A
  • P. ovis: sheep, cattle
  • P. equi: horses
  • P. cuniculi: rabbits
35
Q

Describe Sheep Scab

A
  • Psoroptes ovis
  • Severe pruritus, hypersensitivity, self trauma
  • Economically important
  • Used to be notifiable, no longer the case
36
Q

Describe infestation with Psoroptes

A
  • Very irritant
  • Causes rubbing and trauma
  • Especially in winter
  • Can be zoonotic
37
Q

How is infestation with Psoroptes diagnosed?

A

Skin scrape (if very superficial can use acetone tape)

38
Q

Describe infestation with Chorioptes

A
  • Chorioptes bovis
  • Mange in cattle and horses esp winter
  • Irritant, rubbing but rare trauma (some alopecia where rubbing)
  • Localised infestations and therefore lesions
  • Causes loss of production
39
Q

What are the main locations for Chorioptes infestation in horses and cattle?

A
  • Horses: lower legs “feather mites”
  • Cattle: tail and perineum
40
Q

Describe Otodectes cynotis

A
  • Ear mites in cats and dogs
  • and other carnivores
  • Can be zoonotic
  • Severe irritations
  • Can spread if untreated
41
Q

Describe the clinical signs of infestation with Otodectes cynotis

A
  • Often subclinical
  • Head shaking
  • Continual ear scratching
  • Ear droop
  • Pruritus variable
  • Thick red crusts in external ears of hosts
  • Characteristic black, crusty wax
42
Q

How is infestation with Otodectes cynotis diagnosed?

A

Mites can be seen with otoscope, or microscopic examination of characteristic wax

43
Q

Name the 3 parasitic species of Cheyletiella and give their host species

A
  • C. yasurgi (dogs)
  • C. blakei (cats)
  • C. parasitivorax (rabbits)
44
Q

Describe Cheyletiella

A
  • Largely free living, often predatory
  • 3 parasitic species
  • Cause sclaing, dermatitis and pruritus (usually mild)
  • Aka walking dandruff as move around debris
45
Q

How is infestation with Cheyletiella diagnosed?

A
  • Characterisic “walking dandruff)

- Diagnosed by acetone strip test

46
Q

Name the main species of Trombicula

A

Trombicula autumnalis (chigger or harvest mites)

47
Q

Describe Trombicula

A
  • Free living, only parasitic in larval stages
  • Larvae bright red orange
  • Often found on legs, belly or face/head of grazers
  • Hypersensitivity to bites
48
Q

Describe signs of infestation with Trombicula autumnalis

A
  • Hypersensitivity to bites
  • Pruritus, erythema, scratching
  • Signs contiue after mites have gone as fed mites drop to gound to moult to nymph
49
Q

Name the guinea pig fur mite

A

Chirodiscoides

50
Q

Name the rabbit fur mite

A

Listrophorus

51
Q

Describe Chirodiscoides

A
  • Mites on hair rather than skin
  • Few clinical signs even with large infestation
  • Direct contact, animal bedding or hair and debris for transmission
52
Q

Describe Listrophorus infestation

A
  • More severe signs if heavily infested
  • Problem if already diseased
  • Found on hairs rather than skin
53
Q

Describe Dermanyssus mites

A
  • Chicken red mites
  • Live of bird and take blood meal at night
  • Causes loss of condition, drop in egg production, severe infestation may lead to death due to anaemia
  • Load can build up easily in hutches
54
Q

What are the signs of Dermanyssus infestation?

A
  • Increased dust bathing
  • Balding
  • Looking uncomfortable
55
Q

Describe Ornithonyssus

A
  • Northern fowl mite
  • Blood feeder
  • May spread several infections, but main problem is direct damage
56
Q

Describe the life cycle of Ornithonyssus

A
  • Primarily on host for entire life cycle

- Can live off host for 2-3 weeks

57
Q

Describe the clinical signs of Ornithoyssus infestation

A
  • Greay-black on feathers
  • Chewed feathers
  • Matting and scabbing
  • Reduced production
  • Anaemia
  • Occasionally death
58
Q

Compare the appearance of burrowing and surface mites

A
  • Surface: long legs, some hairier than others, hairs point backwards for grip
  • Burrowing: rounded, short legs, tuck legs in once burrowed
59
Q

How can mites be distinguished?

A
  • Host
  • Appearance
  • Location on host
60
Q

What are the principles of control of mite infections?

A
  • Removal of host infection
  • Treat enviornment in some cases (esp. Ornithonyssus or Dermanyssus)
  • Chemical shampoos and systemic treatments
61
Q

What class and subclass do mites belong to?

A
  • Class: Arachnida

- Subclass: Acari

62
Q

Compare the body parts of insects and arachnids

A
  • Insects: 3 body parts (head, thorax, abdomen)

- Arachnids: 2 body parts (head/gnathosome and body/idiosoma)

63
Q

Describe the life cycle of arachnids

A
  • Hemimetabola

- Most are free living and not parasitic

64
Q

What is mite infestation called?

A

Acariasis

65
Q

What are some general direct effects of acariasis?

A
  • Direct epidermal damage e.g. skin erythema, pruritus, scale formation, lichenification, crust formation
  • Production of cutaneous hypersensitivity
  • Loss of blood or other fluids
66
Q

What are some general indirect effects of mites?

A

May be mechaical or biological vectors of pathogens

Veterinary Medicine Year 2 (30 decks)

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