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| − | {{unfinished}}
| + | #REDIRECT[[:Category:Mites]] |
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| − | {{toplink
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| − | |backcolour =
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| − | |linkpage =Parasites
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| − | |linktext =PARASITES
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| − | |pagetype=Bugs
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| − | |sublink1=Arachnida
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| − | |subtext1=ARACHNIDA
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| − | }}
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| − | <br>
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| − | ==Astigmata Introduction==
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| − | Mites are one of the most successful and divers vertebrate group. The species of veterinary importance are parasitic, although a few non-parasitic mites are also important, such as orbatid and forage mites.
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| − | Mites are very small, on average under 0.3mm in length and for this reason often go unnoticed. They spend the majority of their life cycle '''on''' the host and cause '''mange'''.
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| − | The body shows no segmentation but can be divided into two sections, the '''idiosoma''' and the '''gnathosoma'''. Adult and nymps have '''four''' pairs of legs, whereas larvae have only '''three''' pairs of legs.
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| − | The taxonomy of mites is complex as there are over 8 families. In this article the families are split according to their location on the host into sub-surface (burrowing) and surface (non-burrowing) mites.
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| − | ==Burrowing Mites==
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| − | ===Sarcoptidae===
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| − | ====''Sarcoptes''====
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| − | '''Recognition'''
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| − | *Small, round mite
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| − | *Short legs
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| − | **Project only a short distance from body margin
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| − | *Dorsal spines
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| − | **Arranged in rows
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| − | *Dorsal spines
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| − | *Terminal anus
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| − | *Male is about 250μm in length and the female about 400-430μm in length
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| − | '''Life Cycle'''
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| − | *3 weeks life cycle
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| − | *Female lays eggs in epidermis in an '''egg laying pocket'''
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| − | *Female feeds on liquid ozzing from damaged tissue
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| − | *The eggs hatch in 1 week
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| − | *'''6 legged''' larvae released which crawl to skin surface
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| − | *The larvae then burrow back into the epidermis into '''moulting pockets'''
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| − | *Larvae moult to become '''8 legged''' nymphs
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| − | *Nymphs moult twice before becoming adults
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| − | *Adult males emerge and look for females for mating
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| − | '''Transmission'''
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| − | *Close contact
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| − | *Adults and larvae can be transferred from one skin surface to another
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| − | '''Pathogenesis'''
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| − | *Erthema with papule formation
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| − | *Scale and crust formation
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| − | **Alopecia
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| − | *Intense pruritis for one week
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| − | **Self-inflicted trauma
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| − | **Scab formation
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| − | *Wrinkling anf thickening of skin
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| − | *Hypersensitivity may develop
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| − | **Rash develops
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| − | *''Sarcoptes scabiei
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| − | **In [[Parasitic skin infections - Pathology#Scabies|scabies]]
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| − | *Strains of ''S. scabiei'' can be passed between different animals and cause clinical signs although the infection is likely to resolve spontaneously and be unlikely to establish
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| − | '''Diagnisis'''
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| − | *Skin scraping until capillary blood appears
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| − | **Adults, eggs, immature mites and faecal pellets looked for
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| − | *Place material on a microscope slide
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| − | *Add 10% KOH
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| − | *Warm slide over bunson flame
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| − | '''Treatment'''
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| − | *Acaricide
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| − | **For more information on acaricides click [[Ectoparasiticides|here]]
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| − | *Treat both infected and in-contact animals
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| − | *Older products have to be given in repeat treatments
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| − | *Avermectins are effective in farm animals
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| − | *Selamectin is available as a good spot-on for dogs
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| − | *Control for pigs:
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| − | **Treat sows before entering the farrowing pen
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| − | **Treat boars at 6 month intervals
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| − | =====Sarcoptic Mange=====
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| − | '''Dogs'''
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| − | *Highly contagious
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| − | *Intense pruritis
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| − | *First signs appear at edges of ears, then progresses to muzzle, face and elbows
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| − | '''Cats'''
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| − | *Rare
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| − | '''Pigs'''
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| − | *Important condition as 35% pigs are asymptomatic carriers
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| − | *First signs of infestation appear on the ears before spreading to the rest of the body
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| − | *Transmission from sow to piglets whilst suckling and from boars to gilts at service
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| − | *Infestation adversely affects productivity
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| − | '''Cattle'''
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| − | *Most frequently seen in housed cattle
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| − | *Notifiable in USA and Canada
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| − | *Often called 'neck and tail mange' as lesions most often seen on neck and tail
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| − | *Infestation adversely affects productivity
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| − | '''Sheep'''
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| − | *Notifiable in UK
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| − | *Lesions on hairy parts of face
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| − | **E.g. Face, ears, axillae and groin
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| − | *Causes considerable hide damage in local African breeds of long haired sheep
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| − | '''Horses'''
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| − | *Notifiable in UK
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| − | *Lesions begin on head, neck and shoulders then spread to rest of body
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| − | ====''Knemidocoptes''====
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| − | [[Image:Clinical Case 2 03.jpg|thumb|right|150px|''Knemidocoptes'' Mite under Light microscope (Courtesy of C. Antonczyk)]]
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| − | [[Image:Clinical Case 2 01.jpg|thumb|right|150px|Chicken with Scaly Leg (Courtesy of C. Antonczyk)]]
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| − | *Only genus of burrowing mites which occur on avian species
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| − | *Life cycle similar to ''Sarcoptes spp.''
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| − | *Diagnosis based on clinical signs and discovery of mites
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| − | *Repeat treatments with [[Ectoparasiticides|acaricides]] needed
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| − | **Few products licensed for use in poultry
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| − | '''Recognition'''
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| − | *Small, round mite
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| − | *Short legs
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| − | *U-shaped chitinous bar behind head
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| − | *Terminal anus
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| − | *''K. mutans''
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| − | **Scaly leg in poultry
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| − | **Mites burrow beneath leg scales causing them to loosen and rise
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| − | **Ragged appearance to legs and feet
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| − | **Distorted claws and feet
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| − | **Infected birds are usually lame
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| − | *''K. gallinae''
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| − | **Depluming itch in poultry
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| − | **Burrow into feather shafts
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| − | **Intense pain and pruritis
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| − | **Birds pull out body feathers
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| − | *''K. pilae''
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| − | **Scaly face and beak in psittacines
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| − | **Mites attack bare or lightly feather areas of the face, beak, cere and body
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| − | **Scaliness at the base of the beak is the first sign which then spreads
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| − | **Little pruritis
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| − | ===''Trixacarus''===
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| − | *Similar to ''Sarcoptes'' but half the size
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| − | *Causes severe pruritis in labaratory rodents
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| − | *Burrowing activity causes biting, scratching and irritation
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| − | **Leads to inflammation, pruritis and alopecia
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| − | *Affected areas show acanthosis and hyperkeratosis
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| − | *Death can occur within 3-4 months of infection
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| − | *Transmission is due to close contact between between mother and offspring
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| − | ===''Demodex''===
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| − | *''Demodex'' spp. found on all domestic mammals and on humans
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| − | **Each host has its own species
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| − | *Causes [[Parasitic skin infections - Pathology#Demodicosis|demodicosis]]
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| − | '''Recognition'''
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| − | *Cigar shaped
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| − | *Four pairs of stumpy legs on the anterior end
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| − | *Long and narrow to fit into hair follicles
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| − | '''Life Cycle'''
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| − | *Live as commensal organisms
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| − | *Live in hair follicles and in sebaceous glands
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| − | *Life cycle takes 3 weeks
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| − | '''Pathogenesis and Epidemiology'''
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| − | *Initial infection is slight hair loss which may resolve spontaneously or could spread over the body
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| − | *Squamous demodecosis
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| − | **Less serious
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| − | **Dry reaction
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| − | **Alopecia, desquamation and skin thickening
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| − | **Absent to mild pruritis
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| − | *Follicular/pustular demodecosis
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| − | **More serious
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| − | **Skin invasion by ''Staphylocci''
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| − | **Skin becomes wrinkled, thickened and contains pustules whish ooze serum, blood or pus
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| − | **Affected animals may be seriously disfigured
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| − | **Severe pruritis is associated with secondary infection
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| − | *Immune factors are important in determining the severity and occurence of demodecosis
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| − | **Familial susceptibility
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| − | **Immunosuppression
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| − | **Immunosuppressants
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| − | '''Cats'''
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| − | *Rare
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| − | *Confined to the periocular region
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| − | *Mild squamous type only
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| − | '''Cattle'''
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| − | *Pea-sized nodules in the skin
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| − | **Each nodule contains several thousand mites
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| − | *Affects hide quality
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| − | **Economically important in Australia
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| − | '''Goats'''
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| − | *Becoming more common in goats
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| − | *Disease similar to that in cattle
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| − | ''Pigs, Sheep and Horses'''
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| − | *Rare
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| − | '''Diagnosis'''
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| − | *Liquid parafin applied to a skin fold
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| − | *Deep skin scraping
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| − | '''Control'''
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| − | *Not easily accesible to acaricides due to their deep location in the skin
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| − | *Repeat treatments needed
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| − | *Recovery may take several months
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| − | *To aid [[Ectoparasiticides|acaricide]] penetration, clipping a dog's coat and washing is recommended
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| − | ===''Notoedres''===
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| − | *Known as feline scabies
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| − | *Also common ectoparasites of tropical bats
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| − | *Parasite of cats, rats, man and rabbits
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| − | '''Recognition'''
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| − | *Similar to ''Sarcoptes''
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| − | *Less distinct angles on body surface
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| − | *Females have suckers on legs one and two
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| − | *Females are about 225μm in length and males 150μm
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| − | *Anal opening is distinctly dorsal (not posterior)
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| − | '''Pathogenesis'''
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| − | *Infection begins on the ear tips and spreads over the body
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| − | *''Notoedres cati'' in [[Parasitic skin infections - Pathology#Notoedric mites|notoedric skin infestation]]
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| − | *Causes dermatitis
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| − | *Burrowing of females damages keratinocytes leading to cytokine release
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| − | *Hypersensitivity reaction may occur
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| − | '''Diagnosis'''
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| − | *Superficial skin scraping
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| − | *A single nest in a scraping may yield many mites
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| − | ==Non-Burrowing Mites==
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| − | ===''Psoroptes''===
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| − | *In [[Parasitic skin infections - Pathology#Psoroptic mites|psoroptic skin infestation]]
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| − | ====''Psoroptes cuniculi''====
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| − | *Parasite of rabbits
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| − | *Epizootiology
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| − | **Common among conventional rabbits; transmitted via contact.
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| − | *Clinical
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| − | **The ears are painful and itch intensely; affected rabbits shake their heads and scratch their ears. The inner surfaces of the pinnae are covered with brown, scaly, fetid material, and the skin beneath is raw. Mites are grossly visible.
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| − | *Pathology
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| − | **Histologically, there is chronic erosive and proliferative eosinophilic dermatitis. The mites are non-burrowing and thus are found only in the exudate, not in the tissue.
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| − | *Diagnosis
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| − | **Appearance; examination for mites (low magnification).
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| − | *Control
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| − | **Infestations are difficult to eliminate from a colony, although ivermectin is said to be effective.
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| − | ====''Psoroptes ovis''====
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| − | *Adult females are large mites at 750μm in length
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| − | *Males identified by copulatory suckers and paired posterior lobes
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| − | *Males attach to deutonymphs (second moult after larval stage) in a process called '''copula'''
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| − | **Males remain in copula until females moult for the last time
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| − | **Copulation occurs
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| − | *Life cycle last 14 days
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| − | '''Pathogenesis'''
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| − | *Economically important ectoparasite of sheep
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| − | *Causes '''sheep scab'''
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| − | **Wool loss, restlessness, biting, scratching of infested area and decreased productivity through a decreased weight gain
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| − | *Lesions most common on flanks, neck, back and shoulders
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| − | *Causes pruritic condition of cattle
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| − | ===''Chorioptes bovis''===
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| − | *In [[Parasitic skin infections - Pathology#Chorioptic mites|skin infestation]]
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| − | ===''Otodectes cynotis''===
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| − | *in [[Parasitic skin infections - Pathology#Otodectic mites|otodectic skin infestation]]
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| − | ===''Cheyletiella'' sp.===
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| − | *''Cheyletiella yasguri''
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| − | *In [[Parasitic skin infections - Pathology#Cheyletiellosis|skin infestation]]
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| − | ===''Dermanyssus''===
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| − | ===''Ornithonyssus''===
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| − | ===''Trombicula''===
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| − | *In [[Parasitic skin infections - Pathology#Trombiculidiasis|skin infestation]]
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| − | ===''Leporacarus''===
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| − | ===Forage Mites===
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| − | ===''Varroa''===
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| − | ==Links==
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| − | [[Clinical Case 2]]
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