Difference between revisions of "Parasitic skin infections - Pathology"

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#REDIRECT[[:Category:Integumentary System - Parasitic Infections]]
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{{toplink
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|backcolour = FFCCCC
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|linkpage =Integumentary System - Pathology
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|linktext =Integumentary System
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|maplink = Integumentary System (Content Map) - Pathology
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|pagetype =Pathology
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|sublink1 = Skin Infectious - Pathology
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|subtext1 = SKIN INFECTIOUS
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}}
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<br>
 +
 
 +
==[[Flea Dermatosis]]==
 +
 
 +
==[[Fly Dermatosis]]==
 +
 
 +
===[[Myiasis]]===
 +
 
 +
==Helminths==
 +
 
 +
===[[Habronemiasis, Cutaneous]] ===
 +
 
 +
 
 +
===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
 +
 
 +
===Onchocerciasis===
 +
 
 +
*Caused by [[Onchocerca spp.|''Onchocerca'' spp.]]
 +
*Affects horses, cattle, [[Onchocerciasis - Donkey|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
 +
 
 +
 
 +
==Lice==
 +
 
 +
*Infestation is called '''pediculosis'''
 +
*May cause anaemia ([[Lice|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
 +
 
 +
==Mites==
 +
 
 +
===Cheyletiellosis===
 +
*Caused by [[Cheyletiella spp.''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
 +
 
 +
===Chorioptic mites===
 +
*Host-specific
 +
*In cattle, horses, goats
 +
*Caused by [[Chorioptes bovis|''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
 +
 
 +
===Demodicosis===
 +
*[[Demodex|''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
 +
 
 +
===Notoedric mites===
 +
*Rare but very contagious
 +
*Caused by [[Notoedres|''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|''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|''Psoroptes cuniculi'']] in ear canals of rabbits, horses, goats and sheep
 +
*[[Psoroptes|''P.equi'']] at base of mane, tail and forelock in horses
 +
*[[Psoroptes ovis|''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
 +
 
 +
===Scabies===
 +
*Caused by [[Sarcoptes|''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
 +
 
 +
===Trombiculidiasis===
 +
 
 +
*Harvest mite infestation (chiggers) - [[Trombicula autumnalis|''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|Eosinophils]], [[Mast Cells|mast cells]]
 +
**Intraepidermal mites
 +
 
 +
==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
 +
 
 +
==Ticks==
 +
 
 +
*Local reaction depends on host hypersensitivity and [[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

Revision as of 10:12, 30 June 2010

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()Map INTEGUMENTARY SYSTEM (Map)
SKIN INFECTIOUS



Flea Dermatosis

Fly Dermatosis

Myiasis

Helminths

Habronemiasis, Cutaneous

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

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:


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

Mites

Cheyletiellosis

  • Caused by Cheyletiella spp.''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

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

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

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, tail 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

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:
  • Microscopically:
    • Hyperplastic, spongiotic, superficial perivascular dermatitis
    • Crusting, eosinophil infiltration
    • Mites are not commonly seen, but eggs and feces may be found in stratumn corneum

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:

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

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
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