Mites

Question 1

Mites belong to the class ………….. and the subclass …………..

Answer 1

Arachnida and subclass acari

Question 2

What is acarariasis?

Answer 2

A mite infestation and severe infestation is called mange

Question 3

How many eggs will a female lay?

Answer 3

Only 10-15 but the life cycle is only 1-4 weeks so proliferate rapidly

Question 4

What are the direct effects of mites?

Answer 4

Direct epidermal damage – skin erythema, pruritus, scale formation, lichenification and crust formation.
The production of cutaneous hypersensitivity
Loss of blood or other fluids

Question 5

What are the indirect effects of mites?

Answer 5

Mechanical or biological transmission of pathogens.

Question 6

What are the important genus’ of burrowing mite

Answer 6

Sarcoptes
Trixacarus
Notoedres
Knemidocoptes
Demodex

Question 7

Name the important genus’ of surface mite

Answer 7

Psoroptidae family:
o Psoroptes
o Chorioptes
o Otodectes

Cheyletiella
Trombicula
Dermanyssus

Macronyssidae family:
o Ornithonyssus

Listrophoridae family:
o Chirodiscoides
o Listrophorus

Question 8

Name the host adapted Psoroptes species

Answer 8

Sheep and cattle (P. ovis)
Horses (P. equi)
Rabbits (P. cuniculi)

Question 9

What is the cause of sheep scab?

Answer 9

Psoroptes
Severe, hypersensitivity and self trauma
Economically very important
Was a notifiable disease

Question 10

What is the most common cause of mange in horses and cattle?

Answer 10

Chorioptes bovis
Especially in the winter 
Causes localised infections 
	Often lower legs of horses
	Often tail and perineum of cattle

Question 11

What is the most common ear mite of cats and dogs?

Answer 11

Otodectes cynotis
Clinical signs include head shaking, continual ear scratching, and ear droop, pruritus is variable. Causes a characteristic black crusty wax in ears.

Question 12

What are the main species of Cheyletiella?

Answer 12

C yasurgi (dogs)
C blakei (cats)
C parasitivorax (rabbits)

Cause the walking dandruff appearance

Question 13

What are chigger or harvest mites?

Answer 13

Trombicula spp.
Free living and only larvae are parasitic
Larve are bright red- orange, 0.2mm
Hypersensitivity to bites causes pruritis, erythema, scratching

Question 14

What genus are chicken red mites?

Answer 14

Dermanyssus
(legs on one side)
Mites live off the bird and take a blood mean at night, can bite humans.
Causes loss of condition, drop in egg production and in severe infestations death due to anaemia.

Question 15

Which genus causes grey black on feathers?

Answer 15

Ornithonyssus
Matting and scabbing, especially around the vent
Blood feeder, primarily remains on the host for its entire life cycle. But…these mites can live off the host bird for 2 to 3 weeks.

Question 16

What is the most important species of the sarcoptes genus?

Answer 16

Sarcoptes scabei
The entire life cycle (17-21 days) is spent on the host.
Intense pruritus probably due to hypersensitivity to mite faecal material.
Diagnosis by deep skin scraping in 12 or more affected sites.

Question 17

What species of mite is common on guinea pigs?

Answer 17

Trixacarus caviae

Burrows into the skin and may produce intense pruritus, alopecia, and dermatitis.

Question 18

What mite is found specially around the head and ears of cats?

Answer 18

Notoedres cati

Question 19

Which mite causes scaly face and tassel foot in birds?

Answer 19

Knemidocoptes
Found in all types of domestic and wild birds
Highly contagious
Inflammation and exudate that dries forming hyperkeratosis, lameness, deformities, pruritis, scratching

Question 20

Is demodex a commensal?

Answer 20

Yes in low numbers they live head down in hair follicles and sebaceous glands.

Question 21

What can cause an opportunistic demodex infestation, is demodex infective?

Answer 21

Often secondary to staphylococcal pyoderma

No as its a commensal.

Question 22

What can we use to treat mange?

Answer 22

Avermectins
Lime sulphur (very good for demodex)
Clipping fur and keratolytic shampoos to remove crust and scale
Permethrins, amitraz etc for ear mites
Steroids for demodicosis and pruritus

Question 23

How can we treat the environment (very important for birds) for mange?

Answer 23

Organophosphates

Lime sulphur

Question 24

How many pairs of legs does the female otodectes mite have?

Answer 24

4 pairs but the larvae have 3