Mites

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Kingdom

Phylum

Class

Order

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Animalia

Arthropoda

Arachnida

Acarina

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Four sub-orders of Acarina

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1. Ixodoidea

2. Mesostigmata

3. Prostigmata

4. Astigmata

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Mites vs ticks

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Resemble ticks but smaller

Do not have a hypostome with rows of teeth

Abundant, most free living

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Stigmata

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Respiratory openings

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Body divisions

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Capitulum with palps and chelicerae, and idiosoma

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Life cycle of mites

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Egg, larva, nymphs (proto-, dueto-, trito-), adults

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What kind of parasites are mites?

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Can be intermittent parasites in nests or burrows, or permanent parasites

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Where can mites be found on a host?

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On skin, in ears or respiratory system

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Effect of mites on host

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Blood loss

Irritation

Hair loss

Scab formation

Vectors of viruses and protozoans

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Which of the four sub-orders of Acarina refer to mites?

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Mesostigmata (Gamasid mites)

Prostigmata (Trombidiform mites)

Astigmata (Mange mites)

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Mesostigmata

Back 11

Gamasid mites

Legs at anterior end of body

Many free-living

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Prostigmata

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Stigmata on capitulum at base of chelicerae

Chelicerae adapted for piercing

Feather-like setae

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Astigmata

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Stigmata absent

Front pairs of legs separated from back pairs

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Main genera of Mesostigmata

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Dermanyssus

Ornithonyssus

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Dermanyssus gallinae

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Dermanyssus gallinae

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Red mite of poultry

Very common

Triangular anal plate

Nocturnal blood feeders

Spend most of life in environment

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Hosts of Dermanyssus gallinae

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Birds & mammals

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Life cycle of Dermanyssus gallinae

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Eggs, larva, 2 nymphs

Eggs laid in crevices

Life cycle 7 days

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Pathogenesis of Dermanyssus gallinae

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Anaemia

Irritation

Transmit Borrelia anserina

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Control of Dermanyssus gallinae

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Removal of rubbish and all shelter for mites and spraying with 1% malathion

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Back 21

Ornithonyssus spp

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Ornithonyssus spp

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Fowl mites, referred to as 'starling lice'

Two species: O. bursa, O. sylviarun

Oval anal plate

Feed on birds while in nest

Some on birds all the time

Blood feeders

Not host specific

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On which hosts are Ornithonyssus spp common on?

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Wild birds

Found in bird nests

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Pathogenesis of Ornithonyssus spp.

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O. bursa:

Hypersensitivity on man and animals

Can kill newly hatched chickens and adult birds

Commonly puts birds off the lay

O. sylviarum:

Irritation, anaemia, low fertility in roosters

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Other mesostigmatid mites

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May be uncommon or non-pathogenic

Nasal mite of the dog: Pneumonyssoides caninum

Ear mite of cattle: Raillietia auris

Snake mite: Ophionyssus natricis

Canary lung mite: Sternostoma tracheacolum

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Main genera of Prostigmata

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Trombicula

Demodex

Psorergates

Cheyletiella

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Back 27

Trombicula spp.

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Trombicula

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Chiggers, harvest mites

Only larvae are parasitic

Attach in clusters

Often yellow or orange

Transmit scrub typhus (Rickettsia australis)

T. sarcina causes black soil itch in Qld

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Back 29

Demodex canis

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Features of Demodex canis

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Vermiform

Legs very short at front of body

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Localisation of Demodex canis

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Hair follicles

Feed on cytoplasm

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Life cycle of Demodex canis

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Egg, 2 nymphs, adults

All stages in hair follicles

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Transmission of Demodex canis

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Contact during suckling

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Back 34

Demodectic mange

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Demodectic mange

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All dogs infected, only some develop disease

Short-haired dogs with CMI deficiency

Mainly 6-10 months of age

Predilection sites: eyes, ears, muzzle

Secondary infection with Staph. albus

Infection of follicles leads to hair loss & hyperkeratosis

Disease can be:

- localised or generalised

- squamous or pustular (secondary infection)

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Diagnosis and treatment of Demodectic mange

Back 36

Deep skin scraping

Amitraz

Ivermectin

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Other species of Demodex

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Uncommon or rarely pathogenic

Each host has "own" species

Pig:

- D. phylloides

- lesions mainly on head

Cattle:

- D. bovis

- damages hide

Sheep, goats, horse:

- D. ovis, D. caprae, D. equi

- rare

Man:

- D. folliculorum

- prevalence 50%

- common in blackheads

- base of eyelashes

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Back 38

Psorergates ovis

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Psorergates ovis features

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The sheep itch mite

Tiny mite

Circular with legs arranged radially

Legs very short

Lives in superficial layers of dermis

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Psorergates ovis host

Back 40

Affects sheep in Australia, Africa, N&S America

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Life cycle of Psorergates ovis

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Egg, Larva, 3 nymphs, adults

Length: 5 weeks

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Transmission of Psorergates ovis

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Contact (suckling, shearing)

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Predilection sites of Psorergates ovis

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Sides, between hip & shoulder near mid-line

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Seasonal occurance of Psorergates ovis

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Most abundant in winter

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Effect of Psorergates ovis on host

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Hypersensitivity causes irritation

Rubbing - pulled wool

Not all sheep affected

Spreads slowly in mob

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Diagnosis & treatment

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Skin scraping

Control can be by OPs, amitraz or ivermectin

None will totally eliminate mite

Ivermectin better in spring when mites are reproducing actively

OPs with amitraz good during quiescent phase

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Back 47

Cheyletiella spp

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Cheyletiella genus features

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Palpi short and strong

Strong claws on palps

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Cheyletiella species

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Rabbits: Cheyletiella parasitivorax

Dogs: Cheyletiella yasguri

Cats: Cheyletiella blakei

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Effects of Cheyletiella spp on host

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Mild mange, often around head

Also bite humans

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Two families of Astigmata mites

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Sarcoptidae

Psoroptidae

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Back 52

A = Sarcoptidae

B = Psoroptidae

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Sarcoptidae features

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Rear legs very short

Burrow in upper layers of skin

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Psoroptidae features

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Rear legs project

Tissue fluid feeders cause scabs

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Sarcoptidae genera

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Sarcoptes

Notoedres

Trixacarus

Cnemidocoptes

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Psoroptidae genera

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Psoroptes

Otodectes

Chorioptes

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Sarcoptes scabiei

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Features of Sarcoptidae family

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Body round

Legs 3 and 4 usually do not project beyond body margin

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Features of Sarcoptes scabiei

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Triangular scales on dorsum

Wide host range

Strains on specific hosts

Can survive but not reproduce on other hosts

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Life cycle of Sarcoptes scabiei

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Lives in superficial layers of skin

Lay eggs in tunnel

Larva and 2 nymphal stages

Length: 10-17 days

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How long can Sarcoptes scabiei mites survive off host?

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Few days

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Transmission of Sarcoptes scabiei

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Contact

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Sarcoptes scabiei inside epidermis

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Pathogenesis of Sarcoptes scabiei

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Burrowing mites cause irritation

Intense pruritis

Hyperkeratosis

Alopecia

Lesions begin on face, extend over body

Secondary infection, pustules

Self inflicted trauma

Hypersensitivity

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Diagnosis of Sarcoptes scabiei

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Skin scrapings

Can be difficult to find mites

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Treatment of Sarcoptes scabiei

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Most insecticides

Topical only as sarcoptes mites don't feed on blood

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Sarcoptes scabiei hosts

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Dogs

Other:

Pigs, camels, ferrets, wombats, pigs, humans

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Other sarcoptid genera on mammals

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Guinea pigs: Trixacarus caviae

Cats & rabbits: Notoedres cati

Rodents: Notoedres muris

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Cnemidocoptes spp

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Cnemidocoptes species

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Cnemidocoptes gallinae

Cnemidocoptes mutans

Cnemidocoptes pili

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Cnemidocoptes features

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Sarcoptid mites of birds

Legs very short

Found on birds

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Where is Cnemidocoptes gallinae found?

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In feathers

Depluming mite of poultry

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Where is Cnemidocoptes mutans found?

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On legs of chickens

"Scaly leg"

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Scaly leg

Caused by Cnemidocoptes mutans

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Where is Cnemidocoptes pili found?

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On beak and legs of psittacines

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Cnemidocoptes pili on beak and legs

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Features of Psoroptidae family

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Body oval

Legs 3 & 4 project beyond body margin

Mites don't burrow, but cause scab formation

Tissue fluid feeders

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Genera of Psoroptidae

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Otodectes : ear mite of cats and dogs

Psoroptes: mites of rumnants, horses

Chorioptes: mites of ruminants and horses

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Differentiating between psoroptes and chorioptes

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Psoroptes have jointed pedicels

Chorioptes have simple pedicels

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A = Psoroptes (jointed)

B = Chorioptes (simple)

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Otodectes cynotis

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Otodectes cynotis hosts

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Common ear mite of dogs and cats

Also occurs in foxes and rabbits

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Pathogenesis of Otodectes cynotis

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Causes scabs in external ear canal

Hosts shake heads and rub ears

May get fever and depression in cats

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Transmission of Otodectes cynotis

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Transmitted by contact, often while suckling

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Diagnosis of Otodectes cynotis

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With otoscope, unreliable

Examine exudate under microscope

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Treatment of Otodectes cynotis

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Oral or topical insecticides

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Psoroptes species

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Sheep scab mite: Psoroptes ovis

Ear mite: Psoroptes cuniculi

Psoroptes equi

Psoroptes natalensis

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Back 88

Psoroptes ovis

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Psoroptes ovis features

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Large mite

Lives under scabs

Feeds on tissue fluids

Life cycle 9-10 days

High biotic potential

Most abundant in cool weather

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Pathogenesis of Psoroptes ovis

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"Sheep scab" (but affects cattle too)

Irritation

Scabs

Hypersensitivity

Emaciation, high mortality

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What areas of the animal does Psoroptes ovis affect?

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Starts on shoulders and back, spreads over whole body

In latent cases can occur in ears, inguinal folds, interdigital spaces

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How common is Psoroptes ovis?

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Common in most countries

Eradicated from Australia

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Psoroptes cuniculi

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Hosts of Psoroptes cuniculi

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Rabbit, horse, goat, alpaca

Common in lab rabbits

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Pathogenesis of Psoroptes cuniculi

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Causes ear mange

May spread onto face

Causes irritation, shaking of head

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Chorioptes bovis

(L to R: male, female)

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Chorioptes bovis hosts

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Cattle, sheep, goats, horses

Commonly seen in housed sheep and cattle

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Pathogenesis of Chorioptes bovis

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Chorioptic mange

Often referred to as barn itch

Can cause scrotal mange in rams

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Where on the animal does Chorioptes bovis usually occur?

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Mainly on legs and belly

Sits underneath scabs