Mites

Question 1

• How many body segments & pairs of legs do Acari have?

Answer 1

Two body segments (gnathosoma & idiosoma) & 4 pairs of legs

Question 2

• How can you differentiate the larval stage from other stages?

Answer 2

Larval stage has 6 legs, not the usual 8

Question 3

• What do parasitic mites feed on?

Answer 3

Blood, lymph, skin debris or sebaceous secretions

Question 4

• Describe the life cycle of a mite

Answer 4

Egg -> larvae -> nymph -> nymph -> nymph -> adult

Question 5

• List the common burrowing mites

Answer 5

Sarcoptes, Trixacarus, Knemidocoptes, Demodex

Question 6

• How would you diagnose Sarcoptes?

Answer 6

By deep skin scraping in 12 or more affected sites

Question 7

• What is Trixacarus caviae?

Answer 7

A sarcoptid common in guinea pigs

Question 8

• What mite causes a condition commonly known as scaly face, scaly foot or tassel foot in birds?

Answer 8

Knemidocoptes

Question 9

• What are the two types of demodicosis caused by Demodex?

Answer 9

Localised demodicosis – commonly on the face, and forelegs in young animals
Generalised demodicosis – more severe, widespread from onset, usually underlying disease

Question 10

• List the common surface mites

Answer 10

Pscoptes, Chorioptes, Otodectes, Cheyletiella, Trombicula, Dermanyssus, Ornithonyssus, Chirodiscoides, Listrophorus

Question 11

• What is a highly diagnostic feature of Psoroptes?

Answer 11

Funnel shaped pulvilli attached to three jointed pretarsi, the jointed pretarsi are highly diagnostic since in most other mites they are un-jointed

Question 12

• What are the two most common species affected by Psoroptic mange?

Answer 12

Sheep & rabbits

Question 13

• What species are infected by Chorioptic mange?

Answer 13

Cattle & horses

Question 14

• What are the clinical signs of an Otodectes infection?

Answer 14

Head shaking, continual ear scratching, ear droop, pruritus is variable
Common cause of otitis externa

Question 15

• Which mites have a characteristic waist and large palps that look like an extra pair of legs & causes a condition known as walking dandruff?

Answer 15

Cheyletiella

Question 16

• Which mite is only parasitic during the larval stage?

Answer 16

Trombicula (chiggers or harvest mite)

Question 17

• What are the guinea pigs and rabbits fur mites?

Answer 17

Guinea pig fur mite – Chirodiscoides caviae

Rabbit fur mite – Listrophorus gibbus

Question 18

• How is Listrophorus gibbus transmitted?

Answer 18

Direct contact with the host, animal bedding, or hair and debris

Question 19

• What are the two major mites that affect birds?

Answer 19

Dermanyssus (chicken red mites) & Ornithonyssus (the Northern fowl mite)

Question 20

• How do these two mites differ?

Answer 20

Dermanyssus live off the bird and take a blood meal at night

Ornithonyssus primarily remain on the host for its entire life cycle

Question 21

• How do you control a mite infection?

Answer 21

Need to identify the mite to ensure appropriate treatment can be used

Question 22

• What are the direct and indirect effects of mites?

Answer 22

Direct – direct epidermal damage, the production of cutaneous hypersensitivity, loss of blood or other fluids
Indirect – mechanical or biological transmission of pathogens