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>
 +
 
 +
==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==
 +
 
 +
===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
 +
 
 +
===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, 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'' 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 [[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
 +
 
 +
===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
 +
 
 +
===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
 +
 
 +
===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
 +
 
 +
===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
 +
 
 +
==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 [[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

Revision as of 16:43, 12 January 2009

 This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


WikiPathWikiPath Banner.png
()Map INTEGUMENTARY SYSTEM (Map)
SKIN INFECTIOUS



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

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

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 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, 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

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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