Lecture 23: Parasitic Mites

What morphological differences are there between ticks and mites?

Mites are smaller with a smooth hypostome and most are free-living, but few are paras

What are the 3 basic morphological groups of mites?

Mesostigmatid, astigmatid, prostigmatid

How do mites cause disease to their host?

• may suck blood → anemia

• dermatosis, pierce skin, irritation and inflammation at bite site

• facilitate bacterial infections

What is a stigmata?

openings for respiration

Where is the stigmata located on a mesostigmatid mite?

between the 3rd and 4th pair of legs

True or false: Most mesostigmatid mites are free-living.

True

What morphological group would this mite be placed in?

mesostigmatid

What morphological group is this mite a part of?

Dermanyssus gallinane

What mite is commonly called the red roost mite of poultry?

dermanyssus gallinane

Describe the feeding pattern of dermanyssus gallinane.

vampire model; off the host except when feeding

What is the clinical significance of a dermanyssus gallinane infestation?

anemia resulting from voracious blood sucking habits, especially in young (zoonotic)

What mite is this?

Ornithonyssus sp.

Two common ornithonyssus sp. infect animals. What are they and what species do they inhabit?

• O. sylviarum: poultry

• O. bacoti: rodents

How would you differentiate between dermanyssus gallinane and ornithonyssus spp.?

dermanyssus gallinane have needle-like cheleceria and ornithonyssus spp. have scissor-like cheleceria

What mite is commonly called the Northern Fowl Mite?

O. sylviarum

What makes astigmatid mites unique?

they have no stigmata, so respiration is cutaneous

What is located on the end of the tarsi of astigmatid mites?

suckers

Where do astigmatid mites dwell?

surface dwelling, but can burrow in skin

What is the morphological group of this mite?

astigmatid

What species of mite is this?

psoroptes ovis

Where does the life cycle of the psoroptes ovis mite occur?

on host

How does a psoroptes ovis mite pierce the skin?

needle-like chelicerae

Describe the pathogenesis of psoroptes ovis mites?

the mite feeds on oozing serum and a psoroptic scab is formed from coagulated serum; hair loss from rubbing and inflammation of dermis

How are psoroptes ovis infestations diagnosed?

mites at the edge of the scab

True or false: Psoroptes ovis mites are a non severe mite that are non-reportable.

false: reportable species

What is the predominant species associated with psoroptes ovis?

sheep, but can affect other livestock animals

What species of mite is this?

chorioptes bovis

True of false: Chorioptes Bovis mites are surface dwelling and their life cycle occurs on the host.

true

What is the pathogenesis of a chorioptes Bovis mite?

they do not pierce skin, so they feed on sloughed epidermal and epithelial debris causing superficial mild pruritic, flaky dermatitis on the legs, tail, and pubic regions

How are chorioptes bovis infestations diagnosed?

presence of mites on host in areas of dermatitis

Which of these mites is a reportable species?

the left

Where does the life cycle of the otodectes cynotis take place?

outer ear canal on host

How are otodectes cynotis infestations diagnosed?

ear swab of outer ear canal and observation of mites

What is this species of mite?

otodectes cynotis

What would you expect to see in the ears of a cat infested with otodectes cynotis?

black, waxy cerumen, itching at ears

What is the general morphology of sarcoptes spp.?

skin burrowing mites with chubby bodies and short legs

Where do sarcoptes spp. reside?

their life cycle occurs on host, so they burrow into and tunnel under the skin in the pinna of ear, inguinal and hair-less portions of the body

What do sarcoptes spp. feed on?

serum, fluids, host protein

What are the clinical signs of sarcoptes spp. infestations?

• pruritic, papular, erythema related to burrowing, defecation and eggs laid in tunnels

• sarcoptic scab formed from oozing serum resulting from scratching and self-mutilation

• hair loss from rubbing and inflammation of dermis extends suitable habitat for more mites

How are sarcoptes spp. infestations diagnosed?

presence of mites in a deep skin scrape at the edge of the scab

Are sarcoptes spp. reportable?

yes, in livestock

What species of mite is this?

sarcoptes spp.

What species of mite is this?

Sarcoptes scabiei var canis

What mite is commonly called the canine mange mite?

Sarcoptes scabiei var canis

What reflex is seen in 95% of dogs with reflex infested with sarcoptes?

pineal/pedal reflex

What mite is commonly called feline mange mite?

notoedres

Where is the anus of notoedres mites found?

on terminal margin of ventral surface

Why are notoedres mites easier to demonstrate on skin scrape?

they are more often on surface in fur

What would you use to treat ear mites?

pyrethrin based OTC solutions, milbemite, must clean ears first

What would you use to treat scabies?

revolution, ivermectin, etc

What morphological group of mites are diverse, ranging from totally parasitic forms to free living forms incidentally related to disease?

prostigmatid mites

True or false: prostigmatid mites have tremendous variation in body form

true

What is this?

demodex

What is the life cycle of demodex?

1. adult mites in hair follicles, sebaceous glands, and procaine sweat glands of host

2. females lay eggs in follicles and glands

3. eggs hatch into six legged larvae in follicles and glands

4. larvae molt to eight legged nymphs in follicles and glands

5. nymphs molt to eight legged adults in follicles and glands

True or false: Demodex canis mites can be transmitted to nursing puppies via direct contact with infested dam soon after birth.

true

What are the clinical signs of localized demodectic mange?

erythema usually around muzzle, alopecia around eyes and pinnae

Who is usually affected by demodectic mange?

immune naive animals (obtained from nursing mother)

What are the clinical signs of generalized demodectic mange?

red mange with dry flaky skin, erythema around elbows and boney projections of body, alopecia around eyes and pinnae

True or false: generalized demodectic mange is curable.

false

What species of mite is commonly called walking dandruff mite?

cheyletiella

What species of mite has zoonotic potential and massive palpal claws?

cheyletiella

What species of mite is this?

cheyletiella

What mite is small, nearly microscopic, nuisance associated with intesnse inflammatory responses to infestation from the family trobiculidae?

chigger mites

Describe the pathogenesis of chigger mites.

salivary component used to dissolve/liquefy host tissue for food; resulting necrotized skin forms “stylostome” feeding tube; head attached to host for duration of feeding episode

What stage of chigger mite life cycle is parasitic?

only larvae

Where are chigger mites usually found in cats and dogs?

ears

What is the difference between these two types of mange?

left: demodectic

right: sarcoptic