Difference between revisions of "Demodex"

Revision as of 22:51, 30 March 2010

Demodex canis - Wikimedia Commons

Demodex spp. found on all domestic mammals and in humans
- Each host has its own species

Causes demodecosis

Recognition

Cigar shaped

Four pairs of stumpy legs on the anterior end

Long and narrow to fit into hair follicles

Life cycle

Live as commensal organisms

Live in hair follicles and in sebaceous glands

Life cycle takes 3 weeks

Pathogenesis and epidemiology

Dogs

Initial infection is slight hair loss which may resolve spontaneously or could spread over the body

Squamous demodecosis
- Less serious
- Dry reaction
- Alopecia, desquamation and skin thickening
- Absent to mild pruritus

Follicular/pustular demodecosis
- More serious
- Skin invasion by staphylococci
- Skin becomes wrinkled, thickened and contains pustules which ooze serum, blood or pus
- Affected animals may be seriously disfigured
- Severe pruritus is associated with secondary infection

Immune factors are important in determining the severity and occurrence of demodecosis
- Familial susceptibility
- Immunosuppression
- Immunosuppressant therapy

Cats

Rare

Confined to the periocular region

Mild squamous type only

Cattle

Pea-sized nodules in the skin
- Each nodule contains several thousand mites

Affects hide quality
- Economically important in Australia

Goats

Becoming more common in goats

Disease similar to that in cattle

Pigs, Sheep and Horses

Rare

Diagnosis

Liquid paraffin applied to a skin fold

Deep skin scraping

Control

Not easily accessible to acaricides due to their deep location in the skin

Repeat treatments needed

Recovery may take several months

To aid acaricide penetration, clipping a dog's coat and washing is recommended

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+[[Image:Demodex canis.jpg|right|thumb|150px|''Demodex canis'' - Wikimedia Commons]]
-{{Taxobox
+*''Demodex spp.'' found on all domestic mammals and in humans
-|name               =''Demodex spp.''
+**Each host has its own species
-|kingdom            =Animalia
-|sub-kingdom        =
-|phylum             =[[:Category:Arthropods|Arthropoda]]
-|super-class        =
-|class              =[[:Category:Arachnida|Arachnida]]
-|sub-class          =Acari
-|super-order        =Acariformes
-|order              =
-|sub-order          =Prostigmata
-|super-family       =Cheyletoidea
-|family             =Demodecidae
-|sub-family         =
-|genus              =Demodex
-|species            =''D. canis'', ''D. aurati'', ''D. criceti'', ''D. bovis''
-}}
-==Introduction==
-[[Image:Demodex canis.jpg|right|thumb|150px|''Demodex canis'' - Joel Mills, Wikimedia Commons]]
-''Demodex spp.'' are found on all domestic mammals as well as in humans and are usually a commensal organism. It is a [[Burrowing Mites|burrowing mite]] as opposed to a [[:Category:Non-Burrowing Mites|surface mite]] meaning that it penetrates into the host's tissue. Each host has a specific species of the ''Demodex'' mite. A clinical infection of ''Demodex spp.'' is termed [[demodicosis]].
-==Identification==
+*Causes [[Parasitic skin infections - Pathology#Demodicosis|demodecosis]]
-The ''Demodex'' species have a distinctive cigar shaped appearance under microscopic examination. Adults and nymphs have four pairs of stumpy legs on the anterior portion of the body, compared to larvae which only possess three pairs of legs. These species are Prostigmata, with their breathing apparatus on the anterior portion of their bodies. Prostigmata is a suborder of the class Acari containing mites with anterior breathing apparatus. This distinctive long and narrow appearance allows them to burrow into and remain inside hair follicles. The eggs are also laid into the hair follicles and look relatively long and spindle shaped.
-==Detection==
-Detecting ''Demodex'' species on animals requires the use of either a deep skin scrape or a hair pluck. These samples can then be prepared in liquid paraffin and analysed under a microscope. Adult mites, larvae and eggs may be demonstrable. Detection of a single mite is not diagnostic as they are common commensals, instead the observation of concurrent clinical signs should be used to diagnose [[Demodicosis|demodicosis]].
-==Life cycle==
+'''Recognition'''
-''Demodex'' species complete their <u>entire life cycle within the hair follicles and sebaceous glands of a single host</u>. Their life cycle takes 3 weeks to complete. The female lays 20-24 '''eggs''' at a time into hair follicles. '''Larvae''' are hexapod and are the same in appearance as the adult mites during their 3 larval stages.
+*Cigar shaped
-Transmission between hosts occurs by close contact. Usually these mites will be commensals of the host from a young age due to maternal transfer to the neonate during suckling.
+*Four pairs of stumpy legs on the anterior end
-==Important Species==
+*Long and narrow to fit into hair follicles
-''Demodex canis''
-::This is by far the most commonly seen species of ''Demodex'' causing clinical problems. Its host species is the dog and [[demodicosis]] is usually a secondary opportunistic pathogen due to other underlying conditions.
-''Demodex criceti'' & ''Demodex aurati''
-::Cause [[Mites - Hamsters#Demodicosis|hairloss in hamsters]].
-''Demodex bovis''
+'''Life cycle'''
-::Causes pea shaped nodules in cattle.
+*Live as commensal organisms
-''Demodex merioni''
+*Live in hair follicles and in sebaceous glands
-::Causes [[Mites - Gerbils#Demodecosis|hairloss in gerbils]].
-{{Learning
+*Life cycle takes '''3 weeks'''
-|flashcards = [[Mites_Flashcards|Mites Flashcards]]<br>[[Cytology Q&A 18]]
-|literature search = [http://www.cabdirect.org/search.html?q=title%3A%28Demodex%29&fq=subject_facet%3A%22Demodex%22 ''Demodex'' publications]
-|Vetstream = [https://www.vetstream.com/canis/search?s=mite Mites]
-}}
-==References==
-Forsythe, P (2007) '''Collection and interpretation of clinical samples for dermatological analysis''' ''In Practice 2007 29: 158-16''
-Henfrey, J I (1990) '''Canine Demodecosis''' ''In Practice 1990 12: 187-19''
+'''Pathogenesis and epidemiology'''
+'''Dogs'''
+*Initial infection is slight hair loss which may resolve spontaneously or could spread over the body
-{{review}}
+*Squamous demodecosis
+**Less serious
+**Dry reaction
+**Alopecia, desquamation and skin thickening
+**Absent to mild pruritus
-{{OpenPages}}
+*Follicular/pustular demodecosis
+**More serious
+**Skin invasion by ''staphylococci''
+**Skin becomes wrinkled, thickened and contains pustules which ooze serum, blood or pus
+**Affected animals may be seriously disfigured
+**Severe pruritus is associated with secondary infection
-[[Category:Burrowing_Mites]]
+*Immune factors are important in determining the severity and occurrence of demodecosis
-[[Category:Expert_Review]]
+**Familial susceptibility
+**Immunosuppression
+**Immunosuppressant therapy
+'''Cats'''
+*Rare
+*Confined to the periocular region
+*Mild squamous type only
+'''Cattle'''
+*Pea-sized nodules in the skin
+**Each nodule contains several thousand mites
+*Affects hide quality
+**Economically important in Australia
+'''Goats'''
+*Becoming more common in goats
+*Disease similar to that in cattle
+'''Pigs, Sheep and Horses'''
+*Rare
+'''Diagnosis'''
+*Liquid paraffin applied to a skin fold
+*Deep skin scraping
+'''Control'''
+*Not easily accessible to acaricides due to their deep location in the skin
+*Repeat treatments needed
+*Recovery may take several months
+*To aid [[Ectoparasiticides|acaricide]] penetration, clipping a dog's coat and washing is recommended
+[[Category:Parasites]][[Category:Mites]]

Difference between revisions of "Demodex"

Revision as of 22:51, 30 March 2010

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