Mites & Ticks of Veterinary Significance Flashcards

1
Q

what is the phylum, class, order of mites and ticks

A

phylum: arthropoda
class: arachnida
order: mites and ticks (acarina)

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2
Q

why are mites and ticks important to health and welfare (6)

A
  1. they cause forms of allergic dermatitis associated with pruritis that is often intense
  2. they cause irritation and restlessness
  3. their larvae can invade the body of an animal and cause tissue destruction
  4. some are obligate blood feeders and can cause anemia
  5. they are very effective at transmitting agents of infectious disease so act as vectors (biological or mechanical)
  6. they can be difficult to control
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3
Q

what are examples of allergic dermatitis

A
  1. mange (mites): psoroptes ovis (sheep scab), sarcoptes scabei (sarcoptic mange, dogs), demodex canis (red mange, dogs)
  2. FAD: flea allergic dermatitis (ctenocephalides felis/canis)
  3. pediculosis (louse infection, cattle/sheep)
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4
Q

what is sheep scab caused by

A

psoroptes ovis a non-burrowing mite

highly contagious, severe and debilitating form of mange

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5
Q

is psoroptic mange notifiable

A

yes in scotland

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6
Q

what is the pathogenesis of psorptes ovis

A

caused by allergic (type 1 hypersensitivity) reaction to mite anitgens

generates inflammation and serous exudate –> dries to form scab surrounded by moist border and inflammed skin –> mites active in scab border –> population expands & scabs extend

pruritis causes excessive rubbing, loss of wool & exocriation

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7
Q

what are the clinical signs of sheep scab

A

lighter wool is first visible sign (usually over shoulders)

restless, rub and scratch (wool becomes ragged/stained)

large areas of wool loss along with open bleeding wounds and thickened skin

reduce weight gains –> weight loss and sometimes death

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8
Q

how is sheep scab diagnosed

A

when handled –> easily elicit nibbling relfex

part wool and look for: crusty lesions of scab

skin scrapings from edge of lesion (10% KOH and identify mites)

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9
Q

what mange is caused by a burrowing mite

A

demodex canis

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10
Q

what is the pathogenesis of demodex

A

live in sebaceous glands and hair follicles

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11
Q

how is demodex diagnosed

A

deep skin scraping

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12
Q

what do demodex look like

A

elongated/cigar shaped

4 pairs of stumpy legs

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13
Q

what does transmission of demodectic mange need

A

transmission requires prolonged contact

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14
Q

what are the features of demodectic mange

A

most animals get mild localized mange –> slight hair loss/thickened skin

not usually pruritic

may resolve spontaneously

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15
Q

what is generalized demodecosis associated with

A

genetically inherited immunodeficiency

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16
Q

what does generalized demodecosis cause

A

squamous alopecia, desquamation and skin thickening

17
Q

hat occurs when demodecosis is pustular

A

bacterial invasion of lesions

thickened skin with small pustules

ooze serum, pus, blood, erythema

hyperpigmentation –> red mange

severe disfigurement

requires prolonged treatment

18
Q

what obligate blood feeders cause anemia

A

heavy infestations required

ticks

dermanyssus gallinae –> non-burrowing, red mite of poultry

horse flies –> intense attacks

keds –> heavy infestations lead to anemia

19
Q

what are examples of

A
  1. many flies –> midges, sandflies, tetse flies
  2. fleas
  3. ticks –> bacteria, parasites, viruses
20
Q

what is Ixodes ricinus

A

european sheep tock

I. ricinus is an ectoparasite of all mammals and birds

21
Q

how are different species of ticks identified

A

morphological features

ixodes has anterior anal groove

desmacentor is ornate

i. ricinus is inornate, overlapping spur
i. canisuga no overlapping spur (vestigal)
i. hexagonus has spur but does not overlap

22
Q

what is the lifecylcle of I. ricinus

A

an efficient vector because all stages are obligate blood feeders and feed on multiple hosts in the lifecycle

year 1: larvae quest for host attach and feed for 6 days –> drop to ground and moult to nymphs

year 2: nymphs quest, attach and feeds 6-8 days –> drop to ground and moult to adults

year 3: adults quest and attach –> male and female mate on host –> female feeds for 14 days –> females drops to ground and lays thousands of eggs

lifecycle takes 3 years and requires 3 separate hosts

23
Q

what is the pathogenic significance of I. ricinus

A

secondary infection of lesions can cause disease

  1. blow fly strike (sheep) –> tissue destruction/anorexia
  2. tick pyameia –> staphylococcus –> septicemia/abscesses/arthritis
24
Q

how does Ixodes ricinus transmit significant microbial pathogens

A
  1. red water (protozoa) –> B. divergens –> fever/anemia/hemoglobinuria
  2. tick-borne fever (sheep/cattle/goats/dogs) –> anaplasma (rickettsia) –> fever/abortion
  3. louping ill (viral) (sheep/cattle/grouse) –> flavivirus –> encepahalitis/abnormal gait/death
  4. lyme disease (bacterial) (dogs/horses/cattle) –> B. burgdorgeri –> persistent fever/arthritis/lameness
25
Q

what is squamous demodecosis

A

alopecia, desquamation and skin thickening