Difference between revisions of "Parasitic skin infections - Pathology"
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− | # | + | {{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 - WikiBlood|Eosinophils]], [[Mast Cells - WikiBlood|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 - Pathology|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 |
Revision as of 21:02, 20 August 2008
|
Mites
Demodicosis
- 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 (hyperadrenocorticism, 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 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 macules, papules, crusts
- If chronic -> 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 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 Otodectes cynotis
- In external ear canals of carnivores, occasionally elsewhere
Psoroptic mites
- Occurs in cattle, sheep, horses, goats, rabbits and other animals
- Host-specific
- Psoroptes cuniculi in ear canals of rabbits, horses, goats and sheep
- P.equi at base of mane, ttail and forelock in horses
- 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 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) - Trombicula sp.
- Form tunnels in epidermis by injecting saliva - eat digested tissue fluid
- Intense pruritus
- Grossly:
- Small, red papules or crusts
- Orange to red larvae
- On skin close to plants or the ground
- Microscopically:
- Hyperplastic, superficial perivascular dermatitis
- Eosinophils, mast cells
- Intraepidermal mites
Ticks
- Local reaction depends on host hypersensitivity and 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
- 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
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 - 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 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 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 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 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.
- Affects horses, cattle, donkeys, mules, sheep, goats
- Transmitted by 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 stilesi
- Occurs in cattle, buffalo, goats
- Transmitted by 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
- Epidermal hyperkeratosis, parakeratosis, acanthosis, eosinophilic microabscesses and crusts
Protozoa
- Cutaneous infection may become a part of systemic infection
- Mostly caused by Leishmania
- Transmitted by 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:
- 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