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Parasitic skin infections - Pathology (view source)
Revision as of 12:24, 31 July 2008
, 12:24, 31 July 2008New page: {{toplink |backcolour = FFCCCC |linkpage =Integumentary System - Pathology |linktext =Integumentary System |maplink = Integumentary System (Content Map) - Pathology |pagetype =Pathology |...
{{toplink
|backcolour = FFCCCC
|linkpage =Integumentary System - Pathology
|linktext =Integumentary System
|maplink = Integumentary System (Content Map) - Pathology
|pagetype =Pathology
|sublink1 = Skin Infectious - Pathology
|subtext1 = SKIN INFECTIOUS
}}
<br>
==Mites==
===Demodicosis===
*[[Suborder: Astigmata, astigmatid mites|''Demodex'']] are normal inhabitants of hair follicles and sebaceous glands
*Have to have increased number of immature mites to classify as infestation
*Host-specific
*Occurs in dogs, cattle, sheep, goats, pigs, horses and cats
*Transmits during nursing from dam to offspring
*''Demodex canis'' in dogs:
**Generalised or localised
**Mainly young dogs affected or adults with other disease ([[Adrenal Glands - Pathology#Adrenal Hyperfunction|hyperadrenocorticism]], [[Thyroid Gland - Pathology#Hypothyroidism|hypothyroidism]])
**Often inherited in pure bred
**Grossly:
***Localised: scaly, erythematous, macular, alopecic areas; usually face or front legs
***Generalised: large, coalescing lesions, patches, erythema, alopecia, scales, crusts
**Microscopically:
***Localised: lymphoplasmacytic perifolliculitis with hyperkeratinisation, sebaceous adenitis, low pigment, intraluminal mites
***Generalised: perifolliculitis and follicular hyperkeratosis, follicular pluggingf, bacterial proliferation, bacterial neutrophilic folliculitis
****May cause folliculat rupture -> furunculosis, cellulitis, lymphadenitis and septicaemia
===Scabies===
*Caused by [[Suborder: Astigmata, astigmatid mites|''Sarcoptes scabiei'']]
*Highly contagious
*Mainly in pigs, dogs, also horses, cattle, sheep, goats and cats
*Intense pruritus due hypersensitivity to mites borrowing through stratum corneum
*Usually starts with external pinnae -> head -> neck -> generalised
*Grossly:
**Erythematous [[Skin Glossary - Pathology|macules, papules, crusts]]
**If chronic -> [[Skin Glossary - Pathology|lichenified]], hairless
*Microscopically:
**Hyperplastic, spongiotic, superficial perivascular dermatitis
**Crusting, eosinophil infiltration
**Mites are not commonly seen, but eggs and feces may be found in stratumn corneum
===Notoedric mites===
*Rare but very contagious
*Caused by [[Suborder: Astigmata, astigmatid mites|''Notoedres cati'']]
*Grossly:
**Erythematous papular rash -> scales, crusts, alopecia -> lichenification when chronic
**Start on neck and ears -> head, face, paws -> generalised
*Microscopically:
**Epidermal hyperplasia, spongiosis, crusts
**Superficial perivascular dermatitis
**Eosinophils
===Otodectic mites===
*Caused by [[Suborder: Astigmata, astigmatid mites|''Otodectes cynotis'']]
*In external ear canals of carnivores, occasionally elsewhere
===Psoroptic mites===
*Occurs in cattle, sheep, horses, goats, rabbits and other animals
*Host-specific
*[[Suborder: Astigmata, astigmatid mites#Psoroptes cuniculi|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep
*[[Suborder: Astigmata, astigmatid mites|''P.equi'']] at base of mane, ttail and forelock in horses
*[[Suborder: Astigmata, astigmatid mites|''P.ovis'']] in sheep ('''sheep scab''')and cattle
**Thickened skin and dry scales and crusts
**Starts at withers and spreads due to self trauma
**Microscopically:
***Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
***Eosinophils
===Chorioptic mites===
*Host-specific
*In cattle, horses, goats
*Caused by [[Suborder: Astigmata, astigmatid mites|''Chorioptes'' spp.]]
*Grossly:
**Erythematous, papular, crusty lesions
**Hairless, thickened skin
**Areas usually affected:
***Horses: lower hind legs
***Cattle: lower hind legs, scrotum, perineum, tail, udder, thigh
***Sheep: lower hind legs and scrotum
***Goats: lower hind legs, hindquarters, abdomen
===Cheyletiellosis===
*Caused by ''Cheyletiella'' sp.]]
*Occurs in dogs, cats, rabbits, humans and wild animals
*In dogs and cats: hyperkeratosis - dry, white, scaly dandruff along back
*May be asymptomatic
*Grossly:
**Focal, multifocal or generalised red papules or crusts
*Microscopically:
**Superficial perivascular dermatitis
**Eosinophils
===Trombiculidiasis===
*Harvest mite infestation (chiggers) - [[Suborder: Astigmata, astigmatid mites|''Trombicula'' sp.]]
*Form tunnels in epidermis by injecting saliva - eat digested tissue fluid
*Intense pruritus
*Grossly:
**Small, red [[Skin Glossary - Pathology|papules or crusts]]
**Orange to red larvae
**On skin close to plants or the ground
*Microscopically:
**Hyperplastic, superficial perivascular dermatitis
**[[Eosinophils - Anatomy & Physiology|Eosinophils]], [[Mast cells - Anatomy & Physiology|mast cells]]
**Intraepidermal mites
==Ticks==
*Local reaction depends on host hypersensitivity and [[Suborder: Metastigmata, ticks|tick's]] secretions
*Grossly:
**Focal erosions, erythema, crusted ulcers, sometimes alopecia and nodules
*Microscopically:
**Epidermal and dermal necrosis
**Perivascular of diffuse inflammation and necrotic margins
**Eosinophils, macrophages and lymphocytes in exudate
**May form granulomas containing collagenous fibres and lymphoid follicles within dermis
==Lice==
*Infestation is called '''pediculosis'''
*May cause anaemia (sucking lice), weakness, discomfort and damage to hair or wool
*More common in low temperatures when hair is longer
*Host-specific
*Spread by direct contact
*Most lesions are due to self-inflicted trauma
*Grossly:
**Papules, crusts, secondary excoriations
**Eggs and lice visible in lesions
==Fleas==
*Occurs in cats and dogs mainly
*Irritation caused by enzymes, anticoagulants and histamine-like substances
*[[Skin - immunologic|Hypersensitivity]] to flea saliva may develop
*Young or small animals may suffer from aneamia
*Lesions normally in dorsolumbosacral region, caudomedial thighs, ventral abdomen, flank, neck (cats)
*Grossly:
**Red papules and secondary excoriations
==[[Insecta|Flies]]==
*Bites may cause irritation, anaemia, toxicity or hypersensitivity
*Grossly:
**Wheals and papules around puncture wound
**Hair loss, scales, crusts, erythema
*Microscopically:
**Superficial perivascular dermatitis
**Eosinophilic folliculitis, +/- furunculosis
**Intraepidermal pustules
**Eosinophils and necrosis
===Myiasis===
*Infection by dipterous flies in moist body areas (''eg.'' perineum)
*Commonly affects sheep - [[Bacterial skin infections - Pathology#Ovine fleece rot|ovine fleece rot]]
*Grossly:
**Matted hair or wool, may be in wounds
**Multiple holes or ulcers
**Malodour
*May result in death due to septicaemia or toxaemia
*'''Cuterebra myiasis'''
**Caused by ''Cuterebra'' sp
**Young animals come into contact with eggs on stones or plants
**Nodules with larvae in subcutis + respiration openings to surface
*'''Hypoderma myiasis'''
**Caused by ''Hypoderma lineatum'' or ''H. bovis''
**Mainly affects cattle
**Skin of legs is penetrated -> migration through [[Oesophagus - Anatomy & Physiology|oesophagus]] or vertebral canal to subcutis of back
**Cause subcutaneous nodules with respiration openings
**Larvae in cavity with fibrin and eosinophils surrounded by granulation tissue with eosinophil clusters
*'''Screwworm myiasis'''
**Occurs in Africa, Asia, Central and South America
**Larvaae are deposited in wounds
**Penetrate and liquify tissue
==Helminths==
===Hookworms===
*Caused by [[Ancylostomatoidea|''Ancylostoma'' or ''Uncinaria'']]
*Grossly:
**Red papules -> lichenified alopecic areas
**Mainly of dog feet
**Foot pads may soften with keratinised area separation
**Possible secondary bacterial dermatitis and [[Skin Glossary - Pathology|paronychia]]
*Microscopically:
**Hyperplastic spongiotic perivascular dermatitis
**Eosinophils
**Crusts
**Migration tracts
===Cutaneous habronemiasis===
*In horses (also calles '''summer sores''')
*Caused by ''Habronema'' sp. or ''Draschia'' sp. - spread by [[Insecta|house flies or stable flies]]
*In traumatised or moist soft skin
*Grossly:
**Single or multiple tomorous masses that proliferate and ulcerate
**Red to brown, on section have small gritty yellow to white foci
*Microscopically:
**Nodular dermatitis
**Eosinophils, epithelioid macrophages, multinucleated giant cells
**Larvae and necrotic tissue
**Granulation tissue with neutrophils along ulcerated surface
===Onchocerciasis===
*Caused by [[Onchocerca spp.|''Onchocerca'' spp.]]
*Affects horses, cattle, donkeys, mules, sheep, goats
*Transmitted by [[Insecta|Simulidae and Ceratopogonidae]]
*Hypersensitivity varies with individuals, may occur without any inflammation
*Grossly:
**Adult parasites within connective tissue nodules
**Microfilaria in dermis, especially ventral midline
**Patchy alopecia, erythema, scaling, crusting, change in pigmentation
**Circular areas of dermatitis on forehead appears in some horses
**May also involve keratitis, uveitis and conjunctivitis
*Microscopically:
**Normal to superficial to deep perivascular dermatitis
**Eosinophils, lymphocytes, microfilariae
===Stephanofilariasis===
*Caused by [[Stephanofilaria spp.|''Stephanofilaria stilesi'']]
*Occurs in cattle, buffalo, goats
*Transmitted by [[Insecta|flies]]
*Affects ventral midline (other species affect different areas of body)
*Grossly:
**Foci extending to large areas
**Errect hairs, epidermal haemorrhage, serum exudate -> crusts
*Microscopically:
**Superficial and deep perivascular dermatitis
**Eosinophils, adult and microfilarial parasites
**[[Skin Glossary - Pathology|Epidermal hyperkeratosis, parakeratosis, acanthosis]], eosinophilic microabscesses and crusts
==Protozoa==
*Cutaneous infection may become a part of systemic infection
*Mostly caused by [[Protozoa|''Leishmania'']]
*Transmitted by [[Insecta|sandflies]]
*Occurs in dogs, cats and rodents (also humans)
*Grossly in dog:
**Generalised alopecia
**Silvery white scales
**Nodules and ulcers if more severe
**Mainly on muzzle, ears and eyes where flies feed
*Microscopically:
**[[Skin Glossary - Pathology|Hyperkeratosis, parakeratosis, crusts]]
**Granulomatous nodules in dermis
**Macrophages, some lymphocytes and plasma cells - periadnexal pattern, may affect sebaceous glands
**Organisms may be found extra or intracellularly
|backcolour = FFCCCC
|linkpage =Integumentary System - Pathology
|linktext =Integumentary System
|maplink = Integumentary System (Content Map) - Pathology
|pagetype =Pathology
|sublink1 = Skin Infectious - Pathology
|subtext1 = SKIN INFECTIOUS
}}
<br>
==Mites==
===Demodicosis===
*[[Suborder: Astigmata, astigmatid mites|''Demodex'']] are normal inhabitants of hair follicles and sebaceous glands
*Have to have increased number of immature mites to classify as infestation
*Host-specific
*Occurs in dogs, cattle, sheep, goats, pigs, horses and cats
*Transmits during nursing from dam to offspring
*''Demodex canis'' in dogs:
**Generalised or localised
**Mainly young dogs affected or adults with other disease ([[Adrenal Glands - Pathology#Adrenal Hyperfunction|hyperadrenocorticism]], [[Thyroid Gland - Pathology#Hypothyroidism|hypothyroidism]])
**Often inherited in pure bred
**Grossly:
***Localised: scaly, erythematous, macular, alopecic areas; usually face or front legs
***Generalised: large, coalescing lesions, patches, erythema, alopecia, scales, crusts
**Microscopically:
***Localised: lymphoplasmacytic perifolliculitis with hyperkeratinisation, sebaceous adenitis, low pigment, intraluminal mites
***Generalised: perifolliculitis and follicular hyperkeratosis, follicular pluggingf, bacterial proliferation, bacterial neutrophilic folliculitis
****May cause folliculat rupture -> furunculosis, cellulitis, lymphadenitis and septicaemia
===Scabies===
*Caused by [[Suborder: Astigmata, astigmatid mites|''Sarcoptes scabiei'']]
*Highly contagious
*Mainly in pigs, dogs, also horses, cattle, sheep, goats and cats
*Intense pruritus due hypersensitivity to mites borrowing through stratum corneum
*Usually starts with external pinnae -> head -> neck -> generalised
*Grossly:
**Erythematous [[Skin Glossary - Pathology|macules, papules, crusts]]
**If chronic -> [[Skin Glossary - Pathology|lichenified]], hairless
*Microscopically:
**Hyperplastic, spongiotic, superficial perivascular dermatitis
**Crusting, eosinophil infiltration
**Mites are not commonly seen, but eggs and feces may be found in stratumn corneum
===Notoedric mites===
*Rare but very contagious
*Caused by [[Suborder: Astigmata, astigmatid mites|''Notoedres cati'']]
*Grossly:
**Erythematous papular rash -> scales, crusts, alopecia -> lichenification when chronic
**Start on neck and ears -> head, face, paws -> generalised
*Microscopically:
**Epidermal hyperplasia, spongiosis, crusts
**Superficial perivascular dermatitis
**Eosinophils
===Otodectic mites===
*Caused by [[Suborder: Astigmata, astigmatid mites|''Otodectes cynotis'']]
*In external ear canals of carnivores, occasionally elsewhere
===Psoroptic mites===
*Occurs in cattle, sheep, horses, goats, rabbits and other animals
*Host-specific
*[[Suborder: Astigmata, astigmatid mites#Psoroptes cuniculi|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep
*[[Suborder: Astigmata, astigmatid mites|''P.equi'']] at base of mane, ttail and forelock in horses
*[[Suborder: Astigmata, astigmatid mites|''P.ovis'']] in sheep ('''sheep scab''')and cattle
**Thickened skin and dry scales and crusts
**Starts at withers and spreads due to self trauma
**Microscopically:
***Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
***Eosinophils
===Chorioptic mites===
*Host-specific
*In cattle, horses, goats
*Caused by [[Suborder: Astigmata, astigmatid mites|''Chorioptes'' spp.]]
*Grossly:
**Erythematous, papular, crusty lesions
**Hairless, thickened skin
**Areas usually affected:
***Horses: lower hind legs
***Cattle: lower hind legs, scrotum, perineum, tail, udder, thigh
***Sheep: lower hind legs and scrotum
***Goats: lower hind legs, hindquarters, abdomen
===Cheyletiellosis===
*Caused by ''Cheyletiella'' sp.]]
*Occurs in dogs, cats, rabbits, humans and wild animals
*In dogs and cats: hyperkeratosis - dry, white, scaly dandruff along back
*May be asymptomatic
*Grossly:
**Focal, multifocal or generalised red papules or crusts
*Microscopically:
**Superficial perivascular dermatitis
**Eosinophils
===Trombiculidiasis===
*Harvest mite infestation (chiggers) - [[Suborder: Astigmata, astigmatid mites|''Trombicula'' sp.]]
*Form tunnels in epidermis by injecting saliva - eat digested tissue fluid
*Intense pruritus
*Grossly:
**Small, red [[Skin Glossary - Pathology|papules or crusts]]
**Orange to red larvae
**On skin close to plants or the ground
*Microscopically:
**Hyperplastic, superficial perivascular dermatitis
**[[Eosinophils - Anatomy & Physiology|Eosinophils]], [[Mast cells - Anatomy & Physiology|mast cells]]
**Intraepidermal mites
==Ticks==
*Local reaction depends on host hypersensitivity and [[Suborder: Metastigmata, ticks|tick's]] secretions
*Grossly:
**Focal erosions, erythema, crusted ulcers, sometimes alopecia and nodules
*Microscopically:
**Epidermal and dermal necrosis
**Perivascular of diffuse inflammation and necrotic margins
**Eosinophils, macrophages and lymphocytes in exudate
**May form granulomas containing collagenous fibres and lymphoid follicles within dermis
==Lice==
*Infestation is called '''pediculosis'''
*May cause anaemia (sucking lice), weakness, discomfort and damage to hair or wool
*More common in low temperatures when hair is longer
*Host-specific
*Spread by direct contact
*Most lesions are due to self-inflicted trauma
*Grossly:
**Papules, crusts, secondary excoriations
**Eggs and lice visible in lesions
==Fleas==
*Occurs in cats and dogs mainly
*Irritation caused by enzymes, anticoagulants and histamine-like substances
*[[Skin - immunologic|Hypersensitivity]] to flea saliva may develop
*Young or small animals may suffer from aneamia
*Lesions normally in dorsolumbosacral region, caudomedial thighs, ventral abdomen, flank, neck (cats)
*Grossly:
**Red papules and secondary excoriations
==[[Insecta|Flies]]==
*Bites may cause irritation, anaemia, toxicity or hypersensitivity
*Grossly:
**Wheals and papules around puncture wound
**Hair loss, scales, crusts, erythema
*Microscopically:
**Superficial perivascular dermatitis
**Eosinophilic folliculitis, +/- furunculosis
**Intraepidermal pustules
**Eosinophils and necrosis
===Myiasis===
*Infection by dipterous flies in moist body areas (''eg.'' perineum)
*Commonly affects sheep - [[Bacterial skin infections - Pathology#Ovine fleece rot|ovine fleece rot]]
*Grossly:
**Matted hair or wool, may be in wounds
**Multiple holes or ulcers
**Malodour
*May result in death due to septicaemia or toxaemia
*'''Cuterebra myiasis'''
**Caused by ''Cuterebra'' sp
**Young animals come into contact with eggs on stones or plants
**Nodules with larvae in subcutis + respiration openings to surface
*'''Hypoderma myiasis'''
**Caused by ''Hypoderma lineatum'' or ''H. bovis''
**Mainly affects cattle
**Skin of legs is penetrated -> migration through [[Oesophagus - Anatomy & Physiology|oesophagus]] or vertebral canal to subcutis of back
**Cause subcutaneous nodules with respiration openings
**Larvae in cavity with fibrin and eosinophils surrounded by granulation tissue with eosinophil clusters
*'''Screwworm myiasis'''
**Occurs in Africa, Asia, Central and South America
**Larvaae are deposited in wounds
**Penetrate and liquify tissue
==Helminths==
===Hookworms===
*Caused by [[Ancylostomatoidea|''Ancylostoma'' or ''Uncinaria'']]
*Grossly:
**Red papules -> lichenified alopecic areas
**Mainly of dog feet
**Foot pads may soften with keratinised area separation
**Possible secondary bacterial dermatitis and [[Skin Glossary - Pathology|paronychia]]
*Microscopically:
**Hyperplastic spongiotic perivascular dermatitis
**Eosinophils
**Crusts
**Migration tracts
===Cutaneous habronemiasis===
*In horses (also calles '''summer sores''')
*Caused by ''Habronema'' sp. or ''Draschia'' sp. - spread by [[Insecta|house flies or stable flies]]
*In traumatised or moist soft skin
*Grossly:
**Single or multiple tomorous masses that proliferate and ulcerate
**Red to brown, on section have small gritty yellow to white foci
*Microscopically:
**Nodular dermatitis
**Eosinophils, epithelioid macrophages, multinucleated giant cells
**Larvae and necrotic tissue
**Granulation tissue with neutrophils along ulcerated surface
===Onchocerciasis===
*Caused by [[Onchocerca spp.|''Onchocerca'' spp.]]
*Affects horses, cattle, donkeys, mules, sheep, goats
*Transmitted by [[Insecta|Simulidae and Ceratopogonidae]]
*Hypersensitivity varies with individuals, may occur without any inflammation
*Grossly:
**Adult parasites within connective tissue nodules
**Microfilaria in dermis, especially ventral midline
**Patchy alopecia, erythema, scaling, crusting, change in pigmentation
**Circular areas of dermatitis on forehead appears in some horses
**May also involve keratitis, uveitis and conjunctivitis
*Microscopically:
**Normal to superficial to deep perivascular dermatitis
**Eosinophils, lymphocytes, microfilariae
===Stephanofilariasis===
*Caused by [[Stephanofilaria spp.|''Stephanofilaria stilesi'']]
*Occurs in cattle, buffalo, goats
*Transmitted by [[Insecta|flies]]
*Affects ventral midline (other species affect different areas of body)
*Grossly:
**Foci extending to large areas
**Errect hairs, epidermal haemorrhage, serum exudate -> crusts
*Microscopically:
**Superficial and deep perivascular dermatitis
**Eosinophils, adult and microfilarial parasites
**[[Skin Glossary - Pathology|Epidermal hyperkeratosis, parakeratosis, acanthosis]], eosinophilic microabscesses and crusts
==Protozoa==
*Cutaneous infection may become a part of systemic infection
*Mostly caused by [[Protozoa|''Leishmania'']]
*Transmitted by [[Insecta|sandflies]]
*Occurs in dogs, cats and rodents (also humans)
*Grossly in dog:
**Generalised alopecia
**Silvery white scales
**Nodules and ulcers if more severe
**Mainly on muzzle, ears and eyes where flies feed
*Microscopically:
**[[Skin Glossary - Pathology|Hyperkeratosis, parakeratosis, crusts]]
**Granulomatous nodules in dermis
**Macrophages, some lymphocytes and plasma cells - periadnexal pattern, may affect sebaceous glands
**Organisms may be found extra or intracellularly