Demodex

Question 1

What are the tyupes of mites causing Demodex

Answer 1

Prostigmatid
Mesostigmatid
Metastigmatid

Question 2

What species are included in the prostigmatid?

Answer 2

Demodex: inside skin, feed on sebaceous secretions
Cheyletiella spp: hair coat
Chigger mites of which there are many species e.g Neotrombicula autumnalis: larvae feed only ONCE on the skin of hosts

Question 3

What species are included in the Mesostigmatid species?

Answer 3

RED MITES

Dermanyssus- feed on the blood of birds

Question 4

What species are included in the Metastigmatid species?

Answer 4

Argasisae and Ixoxidae ticks

Question 5

General morph of demodex

Answer 5

4 pairs of short legs 
Elongated/banana-shaped
Colourless/transparent 
Striated hind body (opisthotone)
No hairs or plates on the body 
Short mouth

Question 6

In general about demodex

Answer 6

Are normal inhabitants of the skin
If animal has poor immune system they over porduce=demodicosis
Have sharp, pointed eggs (like bloodflukes) that allow them to penetrate tissues
Offspring can be infected via the mothers milk
Can leave hair follicles and walk around the skin at night

Question 7

Species of demodex (7)

Answer 7

equi- alopecic papules 
caballi- harmless! on eyelids 
bovis- nodules 
caprae- papules 
ovis- seborrhea 
aries- seborrhea in genital region
phylloides- papules in pigs

Question 8

Demodicosis of dogs

Answer 8

Localized/ aquamous
Generalized/ pustular
Pododemodicosis

Question 9

Localized/ squamous

Answer 9

Circumscribed alopecia

Seborrhea around the eye and muzzle

Question 10

Generalized/ pustular

Answer 10

Continuous lesions on the body

Usually accompanied by pyoderma

Question 11

Pododemodicosis

Answer 11

Distal legs

Question 12

Demodicosis of cats

Answer 12

Same as for dogs but may also cause otitis externa

Question 13

Walking dandruff

Answer 13

Predatory mites
Feed on keratin
Dorsal parts of animals

Question 14

Causes of walking dandruff in dogs cats and rabbits

Answer 14

Cheyletiella:

• yasguri: dogs
• blakei: cats
• parasitivorax: rabbits

Question 15

Morphology of Cheyletiella

Answer 15

Thickened palps with CLAWS
Praetarsus has comb 
White/colourless body
Sparsely scattered hairs 
Dorsal plate: scutum

Question 16

Larvae mites/ HArvest mites/ CHIGGER mites

Answer 16

Predatory
Live in soil
Only the LARVA feed on the tissue fluids of vertebrates by injecting saliva into the skin and then using their stylostome to suck it out
- therefore only the larvae are parasitic, the nymph and adults are predatory
Holes in the skin remain

Question 17

General morph of Larvae mites

Answer 17

Bright orange/red
Short palps (but are longer than the demodex sp)
Scattered, dense haircoat
Claws on tarsus
Dorsal plate= scutum
Larvae: hairy, 3 pairs of legs and are often attached to the keratinous part of the skin

Question 18

Red mites of Po

Answer 18

Mesostigmatid
Blood-sucking at NIGHT, hide in cracks during the day as they don’t like light
Dermanyssus sp are temp on hosts
Can cause anaemia

Question 19

General morph of red mites

Answer 19

Dark red/ Black body
Long legs 
Long/cyclindrical palps 
V. long protrudable chelicerae 
Claws on tarsus 
Dorsal and ventral plates

Question 20

Metastigmatid- types of ticks

Answer 20

Agasidae= soft ticks 
Ixodidae= hard ticks

Question 21

In general about soft ticks

Answer 21

No visible mouthpart from above (except larvae)
No shield 
Feed for short times freq (not larvae)
2-8 nymphal stages 
Painful bite

Question 22

2 soft ticks species affecting birds

Answer 22

Argas persicus

Argas???

Question 23

In general about argas species

Answer 23

Temp
Blood-sucking 
Larvae, nymph and adults feed several times at night 
Vectors 
Mostly host-specific 
May cause anaemia

Question 24

General morph of soft tick species

Answer 24

Yellow/brown grey
Mammilated, leathery soft cuticle- looks like 'backpack' that is full when fed!
Capitulum in ventral side
No sexual dimorphism
Circular body

Question 25

In general about hard ticks

Answer 25

Visible mouthpart from above 
Dorsal shield
Larva, nymph and adults feed slowly and ONCE 
ONE nymphal stage 
Painless bite 
Temporary
Obligate blood-sucking 
Not strictly host specific

Question 26

General morph of hard ticks

Answer 26

Only in males does the shield cover the entire body
When not fed- same size as poppy seeds
Colour varies 
Short and wide palps 
Shield on back
Plates on ventral side 
Capitulum visible dorsally 
Body margin becomes rounded when engorged (not the case for males)
Strong sexual dimorphism
Haller's organs on legs

Question 27

What is the life-cycle of I.ricinus

Answer 27

3-8 years

Question 28

Whatare the 2 basic types of Ixodidae

Answer 28

Nidicolous= endophillic: ‘stays in nest’ e.g hexagonous (hedgehog tick)
Non-nidicolous=exophilic: ‘leaves the nest’ e.g ricinus (sheep tick)

Question 29

Hunting ticks

Answer 29

Dermacentor reticularis 
Hyalomma marginatum 
Have eyes 
Adult= exophillic 
Larvae and nymphs= endophillic

Question 30

Main general of Ixodid ticks

Answer 30

Ixodes spp
Haemaphysalis spp
Dermacentor spp.
Rhipicephalus (+boophilus)

Question 31

Ixodes spp

Answer 31

Dark plain scutum

No eyes

Question 32

Haemaphysalis spp

Answer 32

Lighter, plain scutum

No eyes

Question 33

Dermacentor spp

Answer 33

Scutum is ornamneted

Have eyes

Question 34

Rhipicephalus spp

Answer 34

Brown scutum
Have eyes

Brown dog tick: hepatozoon canis and babesia gibsoni