Parasitology - Exam 1 Lecture 7 (Mites) Flashcards
Regarding mites, discuss the basics
- Short life cycle (<1 month)
- Cause dermatitis that is refrred to as ‘mange”
- some burrow depply into skin and/or hair follicles, and some live superficially within keratin
- the hypostone is the part of the mite that pierces the skin when it bites
- the adult stage has 8 legs
Discuss the life cycle of Mites
Mites: Life cycle
- Incomplete metamorphosis
- Egg –> Larva –> Nymph –> Adult
Discuss the different species of mites
- Sarcoptes scabiei –> pruritic dermaitis of many domestic animals
- Notoedres –> similar to sarcoptes but on cats
- Psoroptes –< scabby lesions of large animals and rabits
- Chorioptes: mild flaky dermatitis of large animals
- Demodex –> nomral flora of most species: can be severe in dogs
- Otodectes: eat mite of dogs and cats
- Pneumonysssoides –> nasal mite of dogs
- ## Dermanyssus, ornithonyssus, Knemidocoptes –> birds
Discuss identification of mites
- Mostly based on length and shape of pedicles
- ## location and host
Regarding sarcoptes scabiei, discuss the basics of it, transmission, and the luife cycle
- Can infest many species but the subspecies are host specific –> Cats and guinea pigfs are not susceptible
Life cycle:
- whole life cycle occurs on host
- **adult burrows deep ** in the skin
- eggs are laid in the burrows that the adukts make
Transmission: primarily, sarcoptes scabiei reuqires direct contact to be transferred
- indirect contact transmission from bedding is possible
Discusss the pathology of sarcoptes sabiei and the amin point of it
Pathology: dermaitis is caused by the damage and inflammatoopn produced byu the burrowing mites
Main point: a lot of the damage is a direct result off self mutiliation by the dog itself because sarcoptic mange is so dman itchy; the dogs with sarcoptic mange often times have t be put on secondary antibiotics to treat/manage the secondary infecrions
Discuss the lcinical signs and diagnosis of sarcoptes scabiei
also discuss treeatmet
- intense pruritis
- self mutiliation
- hair loss
- weight loss
- secondary bacterial infections
Diagnosis: involves the pinnal-pedal reflex where gently scratching the pinna causes animal to lift rear leg to scratch - helpful in making presumtpive diagnosis
- deep skin. scrape –> sample multiples sites (crusty ear margins or elbows/hocks
- skin biopsies (if scrapes are negative)
- treat anyways if negative
Treatment:
- clean and clip affected areas and remove crusts
- must be repeated several times over several weeks
- treeat all animals in contact
- Dogs: topical selamectin; topical moxidectin + imidacloprid
- Livestock (cattle): macrocyclic lactones such as topical eprinomectin can be used on lactating dairy catt;e
Discuss the zoonotic potential of sarcoptes scabieie
- Sarcoptes is zoonotic
- sarcoiptes can be trabnsmnitted from animals to humans byt the symtpoms in humans are transient and the infection is self limiting
Regarding Notoedres, discuss the dmaage to host, diagnsois, treatment and zoonotic potential
- Notodres –> rare cause of mange in cats, rats, and rabbits; referred to as sarcoptic mange in cats
- dmage to host: **dermatitis ** starts on the medial edge of the pinna of ear; moves from ears > face > paws > hindquarters
- Diagnosis: skin scraping is usually easy to the see the miytes
- Treatment: topical selamectin, ivermectin, weekly lime sulfur dips x 6
- ## Zoonotic: self limtiging in humans
Regarding Psoroptes spp, discusss the basics
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- hosts: cattle, sheep, camelids, rabbits
- Like sarcoptes, suubspecies are host specific
- Also refrred to as sheep scab
Discuss thr life cycle of Posorptes spp
- Does not burrow - live at the base of the hair and feed on skin exudates
- Whole life cyle on host: adults can survive a couple of weeks off the host, so Psoroptes is very contagious
Discuss the tranbsmission of Psoroptes spp
- Direct contact: becauase all life stages are on the host, direct contact is the main mode of transmission
- inbdirect contact: brushes, combs, tack, etc shared between animals
- From enviornemnt: transmission cna occur between contact with contaminated pastures, feces, etc
- Asymptomatic carriers can transmit to others in the group
Discuss the pathology pf Psoroptes
- Pieces skin with pointed mouthparts > serum exudation and scab fomration
- **Hypersensitivity ** reaction to mite feces produces crusts –. INTENSE PRURITIS
Discuss the clinical signs of Psoroptes spp
- yellowish scaly crusty lesions form starting at the shoulders and neck
- animal is pruitis, and rubs and bites at the affected area
- infesttaion causes decreased appetite, weight loss, anemia, and secondary bacterial infections
- infestation is rapidly fatal in lambs
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Discuss the treatment for Psoroptes spp
- Treatment of livetsock is same as sarcoptes: 1) clean and clip 2)macrocyclic lactones, organophgosphates, pyrethrins
- **must treat enviornmnt or vacate pasture for 2-4 weeks ** to prevent reinfestation
What species is associated with “barn itch” or “leg mange”
- Chorioptes spp
- most common mange mite on horses and cattle
- prefers: tail, hind legs of cattle and horses
- Forelegs of sheep, goats, camelids
- Usually mildly pruritic flaky dermaitiis
Transmission: direct contact; indirect contact (brushes, combs that are shared between animals –> does not live long off host, therefore, enivonrmental conta,imnation is NOT an issue
Discuss the clinical signs of Chorioptes spp
- often aysmptomatic
- mild, flaky dermatitis on legs and pevlvic region
- mostly kept when animls are kept inside, during the winter
- Knonw as “barn itch”
Discuss the diagnosis of chorioptes spp and also the treatment
- Diagnosis: skin - scrape –> superficial is sufficient
- Treatment: same as sarcoptes: **eprinomectin, ivermectin, moxidectin, doramectin
- dips of lime sulfur, organophosphates, pyrethrins**
What does demodex infection look like
Discuss the demodex spp lifecycle
Discuss Localized demodicosis
- Localized alopecia - around eyes, mouth, and bony projections
- usually occurs in puppies less than 6 months, but can occur in older dogs
- 90% resolves with sexual maturity
- does NOT require treatment
Generalized demodicosis
- Results from a **defect in cell mediated immunity due to underlying disease/condition
- can occur in juvenile or adult dogs
- large area of body affected
- skin becomes coarse and dry, generlaized alopecia, thickend skin, erythema –> “Red mange” –> its nonpruitic
secondary staphylococcal bacterial infections are inevitable
Main point: Demodectic range on its own is not itchy, but if bacterial pyoderma develops it can be very itchy
Predispoising conditons: anything that suppressses the immune system:
- poor nutritioon, co-infections, steroid administartion, tumors, stress, estrus, and parturition
Discuss Otodectes –> ear mite
- Found in **external ear canal ** of dogs, cats, ferrets
- Note that otodectes has a very short pediicel
Does not burrow –> easy to diagnose with an ear swab
Transmission: Direct contact
- infections can cause intense irritation due to hypersensitivity
- Zoonotic: humans can pick it up fromm sleepoing with their animals
Discuss the clinical signs of Otodectes
- Intense prutiis - results in self inflicted ear damage
- can cause a generalized dermatitis
- if left unrtreated, it can cause permanent ear damage
Discuss Cheyletiella
- Known as “walking dandryff” Fur mite
- large palpal clqws/hooks
- causes an exudative, flaky dermatiis which the mite stir up wioth their movemnts
- Transmission: survive a long time off the host, and are very mobiile, so are very contagious
- Diagnosis: Put patients on a darj surface and look for moving white specks
- Treatment: none are approved; topical imidaclopramide/moxidectin or selamectin, topical pyremethrin, or fipronil
Discuss Pneumonoyssoides
Pneumonysoides is the nasal mite of dogs
- lives in nasal passages and sinuses of dogs and cats
- Transmission: Highly mobile, easily transmitted by direct contact
- Dmaage to host: irritation, nasal discharge, sneezing, rverse sneeziung
- Diagnossi: mites can be seen in nasal secretioons and external nares
- Treatment: subcutaneous ivermectin or mibemycin
What species is associated eith bird mites
Blood feeding mites:
- **dermanyssus: found in the nest
- Ornithonyssus:remains on the bbird
Scaly leg and scaly face mites: Knemidocoptes: burrows under scales and deforms feet and face
