Difference between revisions of "Systemic Mycoses"

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#REDIRECT[[:Category:Systemic Mycoses]]
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|linkpage =Fungi
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|linktext =FUNGI
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<br>
 +
 
 +
==Adiaspiromycosis==
 +
 
 +
*Haplomycosis
 +
 
 +
*''Emmonsia crescens''
 +
**Does not proliferate within the animal body
 +
**Each spore develops into a thick-walled spherule called an '''adiaspore'''
 +
 
 +
*''Chrysosporium parvum, C. crescens''
 +
 
 +
*Non-contageous, pulmonary mycosis
 +
 
 +
*Worldwide
 +
 
 +
*Found in soil
 +
 
 +
*Affects burrowing rodents and small animals
 +
 
 +
*Respiratory infection
 +
 
 +
*Spetate hyphae with large numbers of small, round conidia either singly or in groups on the ends of the short conidiospores can be seen
 +
 
 +
*Dimorphic
 +
 
 +
*Grows on Sabauraud's Dextrose agar and Blood agar
 +
==Aspergillosis==
 +
[[Image:Aspergillus cleistothecia.jpg|thumb|right|150px|Aspergillus cleistothecia - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Aspergillus swan.jpg|thumb|right|150px|Aspergillus in a swan - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Aspergillus in vivo.jpg|thumb|right|150px|Aspergillus in vivo - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Aspergillus sporing heads.jpg|thumb|right|150px|Aspergillus sporing heads - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Canine nasal asper radiograph.jpg|thumb|right|150px|Canine nasal aspergillus radiograph - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
*Worldwide
 +
 
 +
*Widely found in nature
 +
**Colonise a wide range of substrates under different environmental conditions
 +
**Abundant in hay, straw and grain which have heated during storage
 +
 
 +
*Common laboratory contaminants
 +
 
 +
*Pathogenic species include ''Aspergillus fumigatus, A. flavus, A. nidulans, A.niger'' and ''A. terreus''
 +
 
 +
*May cause primary or secondary disease
 +
**Infection may be acute, chronic or benign
 +
 
 +
*Avians:
 +
**Diffuse infection of the [[Avian Respiration - Anatomy & Physiology#Air Sacs|air sacs]]
 +
**Diffuse pneumonic form
 +
**Nodular form involving the [[Avian Respiration - Anatomy & Physiology#Avian Lungs|lungs]]
 +
**Spores are inhaled
 +
**Yellow nodules in the [[Avian Respiration - Anatomy & Physiology#Avian Lungs|lungs]] and [[Avian Respiration - Anatomy & Physiology#Air Sacs|air sacs]]
 +
**The acute form usually affects young birds and is rapidly fatal (within 24-48 hours)
 +
***Signs include [[Intestine Diarrhoea - Pathology|diarrhoea]], listlessness, pyrexia, loss of appetite and loss of condition
 +
***Sometimes convulsions may occur
 +
***Resembles Pullorum disease
 +
**The chronic form usually occurs in adult birds and is sporadic, presenting with milder clinical signs
 +
 
 +
*Cattle:
 +
**Infection can cause abortion and ocular infections
 +
**Infections involve the [[Female Reproductive Tract -The Uterus - Anatomy & Physiology|uterus]], [[Foetal Membranes - Anatomy & Physiology|fetal membranes]] and fetal skin
 +
**Lesions are usually up to 2mm in diameter and contain asteroid bodies with a germinated spore in the centre
 +
***Acute infection causes miliary lesions
 +
***Chronic infections causes granulomatous and calcified lesions
 +
 
 +
*Horses:
 +
**[[Guttural Pouches Inflammatory - Pathology|Guttural pouch mycosis]] common
 +
**Infection can cause abortion
 +
**May cause [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
 +
 
 +
*Dogs, cats and sheep:
 +
**Infections occur, but infrequently
 +
**[[Lungs - Anatomy & Physiology|lungs]] and [[Nasal cavity - Anatomy & Physiology|nasal cavity]] most usually affected
 +
**Disseminated form with granulomas and infarcts can occur in dogs
 +
**Pulmonary and intersitital forms can occur in cats
 +
 
 +
*Humans:
 +
**Primary and secondary infections
 +
**[[Lungs - Anatomy & Physiology|lungs]], [[Skin - Anatomy & Physiology|skin]], [[Nasal cavity - Anatomy & Physiology|nasal sinuses]], [[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|external ear]], [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], [[Bones and Cartilage - Anatomy & Physiology|bones]] and meninges all affected
 +
**Infection occurs most frequently in immunocompromised patients
 +
 
 +
*Grows on Sabauraud's Dextrose and Blood agar
 +
**White colonies intitially which turn green, then dark green, flat and velvety
 +
**Colony colour varies with species
 +
 
 +
*Also grows on Czapek-Dox agar and 2% malt extract agar supplemented with antibacterial antibiotics
 +
 
 +
*Microscopically:
 +
**Conidiophores with large terminal vesicles (only visible in the [[Lungs - Anatomy & Physiology|lungs]] and air sacs where there is access to oxygen)
 +
***Vesicle shape varies depending on the species
 +
**Is a common contaminant so repeated tests should be done for a definitive diagnosis
 +
 
 +
*Serology:
 +
**Gel immunodiffusion for canine nasal asper
 +
 
 +
*Treatment:
 +
**Surgery
 +
**Antifungal drugs
 +
***[[Antifungal Drugs#The Azoles|Ketoconazole]], [[Antifungal Drugs#Polyene Antifungals|Nystatin]], [[Antifungal Drugs#Polyene Antifungals|Amphotericin B]], [[Antifungal Drugs#Flucytosine|5-fluorocytosine]], [[Antifungal Drugs#The Azoles|Thiabendazole]]
 +
 
 +
*Pathology:
 +
**''Aspergillus fumigatus'' causes [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]], [[Respiratory Fungal Infections - Pathology#|respiratory tract inflammation]] and [[Paranasal Sinuses Inflammatory - Pathology#Infectious causes of sinusitis|sinusitis]]
 +
**Sometimes appears on [[Nasal Cavity Hyperplastic and Neoplastic - Pathology#Progressive ethmoidal haematoma|lesions of ethmoidal haematoma]]
 +
 
 +
==Blastomycosis==
 +
 
 +
*North America
 +
**Most common in the North-Central and South-Eastern states
 +
 
 +
*Caused by ''Blastomyces dermatitidis''
 +
 
 +
*Widespread in soil
 +
 
 +
*Respiratory infection
 +
 
 +
*Lesions start in the [[Lungs - Anatomy & Physiology|lungs]]
 +
**Haematogenous dissemination
 +
**Can be found in lesions in the eyes, brain, bones and genitalia
 +
**Fatal if not treated
 +
 
 +
*Lesions are also found on the skin
 +
*These may ulcerate
 +
 
 +
*Granulomatous nodules
 +
 
 +
*Affects mainly dogs (and humans)
 +
**Can affect cats, horses, dolphins, ferrets and sealions but is rare in these species
 +
 
 +
*Microscopically:
 +
**Large, spherical, thick-walled cells
 +
**Single buds connected to a mother cell by a wide base
 +
**Double contoured effect of cells
 +
 
 +
*Grows on Sabauraud's Dextrose and Blood agar
 +
**On Sabauraud's Dextrose colonies appear moist and grey with a white cotton-like mycelium which turns tan, brown and then black
 +
***Septate hyphae
 +
***Small, oval/pyriform conidia
 +
***Older cultures have thickened walls
 +
**On Blood agar colonies are creamy in colour, waxy and wrinkled
 +
***Thick-walled budding yeast cells can be seen
 +
 
 +
*Diagnosis:
 +
**Complement fixation test
 +
**Falling antibody titres indicate a poor prognosis
 +
**ELISA and counterimmunoelectrophoresis can also be used
 +
 
 +
*Treatment:
 +
**[[Antifungal Drugs#Polyene Antifungals|Amphotericin B]]
 +
**[[Antifungal Drugs#The Azoles|Imidazoles]]
 +
 
 +
==Coccidioidomycosis==
 +
[[Image:Coccidioidomycosis.jpg|thumb|right|200px|Coccidioidomycosis spherule histopathology - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
*''Coccidioides immitis''
 +
 
 +
*Ocurs in the soil
 +
**Respiratory infections
 +
**Most commonly seen following dust storms
 +
 
 +
*Occurs in arid regions
 +
**E.g. South West USA and Mexico
 +
 
 +
*Non-contageous, systemic mycosis
 +
 
 +
*Affects dogs, cattle, sheep and humans
 +
 
 +
*Mainly affects the [[Lungs - Anatomy & Physiology|lungs]]
 +
**Dissemination can occur to other organs
 +
 
 +
*Causes nodule or granuloma formation
 +
**Localised
 +
**Gross lesions resemble [[Mycobacteria spp.#Bovine tuberculosis|Tb]] in cattle as are usually seen in the bronchial and mediastinal [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] and occasionally [[Lungs - Anatomy & Physiology|lungs]]
 +
**Dissemination can occur, especially in primates and dogs, to the [[Lungs - Anatomy & Physiology|lungs]], [[Liver - Anatomy & Physiology|liver]], [[Spleen - Anatomy & Physiology|spleen]], [[Nervous System - CNS - Anatomy & Physiology|brain]] and [[Bones and Cartilage - Anatomy & Physiology|bones]]
 +
 
 +
*Thick-walled spherules in tissue
 +
**Large sporangia burst leaving 'ghost' spherules
 +
 
 +
*Saprophytic phase consists of coarse, septate, branching hyphae which fragment into thick-walled, barrel-shaped arthrospores which alternate with empty cells
 +
**Stained by Lactose Phenol Cotton Blue
 +
 
 +
*Grows on Sabouraud's Dextrose agar and Blood agar
 +
**Flat, moist colonies which develop a coarse, cotton-like aerial mycelium which varies from white to brown in colour
 +
 
 +
*Complement fixation test, latex agglutination and immunodiffusion tests can all be used
 +
**A positive skin test indicates exposure
 +
 
 +
==Entomophthoromycisus==
 +
 
 +
*Basidiobolmycosis
 +
 
 +
*Caused by ''Basidiobolus'' and ''Conidiobulus'' fungi
 +
 
 +
*Causes ulcerative granulomas in subcutaneous tissue
 +
 
 +
*Affects the oral and nasal mucous membranes
 +
 
 +
*''Basidiobolus'' causes large lesions which may involve skin on the head, neck and chest
 +
**Fistulous tracts
 +
**Extends to [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]
 +
 
 +
*Produce flat, waxy colonies which become white and fizzy over time
 +
 
 +
*Microscopically:
 +
**Septate hyphae
 +
 
 +
*Treatment:
 +
**Surgical excision
 +
**[[Antifungal Drugs#Polyene Antifungals|Amphotericin B]] or [[Antifungal Drugs#The Azoles|Ketoconazole]]
 +
 
 +
==Histoplasmosis==
 +
{| align="right"
 +
|<gallery>Image:Histoplasmosis canine spleen.jpg|<center><p>'''Histoplasmosis in a canine spleen'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center></gallery>
 +
|}
 +
 
 +
*''Histoplasma capsulatum''
 +
 
 +
*Non-contageous, systemic mycosis
 +
 
 +
*Commonly pulmonary infections occur
 +
**Other organs can be involved
 +
**Involves the reticuloendothelial system
 +
**Intestinal form can also occur
 +
 
 +
*Acute and chronic disease can occur
 +
 
 +
*Endemic to the USA
 +
**Isolated cases have been reported in Europe
 +
 
 +
*Respiratory infection
 +
**Infection via ingestion can also occur
 +
 
 +
*Affects dogs, cats, cattle, horses and humans
 +
 
 +
*Found in soil contaminated by bird droppings, decaying vegetation and in caves inhabited by bats
 +
{| align="right"
 +
|<gallery>Image:Histoplasmosis lung.jpg|<center><p>'''Histoplasmosis lesions in lungs'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center></gallery>
 +
|}
 +
*Fine, branching, septate hyphae with smooth-walled pyriform to spherical microconidia and large, thick-walled tuberculate macroconidia on simple conidiophores
 +
 
 +
*Dimorphic fungi
 +
 
 +
*Hard to demonstrate in smears as the organisms is very small
 +
**Stain with Giemsa or Wright and examine under oil immersion lens
 +
 
 +
*Present intracellularly in [[Macrophages - WikiBlood|macrophages]] as oval yeast cells with few buds
 +
**Clear halo is seen around the darker staining central material
 +
 
 +
*Grows on Sabouraud's Dextrose agar
 +
**Creamy white colonies, turning tan coloured and then brown
 +
 
 +
*Also grows on Blood agar
 +
**Small, white yeast-like colonies
 +
 
 +
*Test using immunodiffusion, complement fixation and counterimmunoelectrophoresis
 +
**Skin test of little value as it only indicates exposure
 +
 
 +
*Treatment with [[Antifungal Drugs#Polyene Antifungals|Amphotericin B]]
 +
**If [[Antifungal Drugs#Polyene Antifungals|Amphotericin B]] is contra-indicated, [[Antifungal Drugs#Imidazoles|imidazoles]] can be given orally
 +
 
 +
*The prognosis is poor in acute and disseminated cases
 +
 
 +
 
 +
{| align="center"
 +
|<gallery>Image:Histoplasmosis canine spleen silver stain.jpg|<center><p>'''Histoplasmosis in a canine spleen using silver stain'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center>
 +
Image:Histoplasmosis phagocyte.jpg|<center><p>'''Histoplasmosis phagocyte'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center>
 +
Image:Histoplasmosis tuberculate chlamydospores.jpg|<center><p>'''Histoplasmosis tuberculate chlamydospores'''</p><sup>Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup></center></gallery>
 +
|}
 +
 
 +
==Zygomycosis==
 +
[[Image:Mucor liver.jpg|thumb|right|150px|Mucor liver - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Mucor rumen.jpg|thumb|right|150px|Mucor mould on the ruminal surface- Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Saprolegnia salmon.jpg|thumb|right|150px|Saprolegnia salmon - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Saprolegnia.jpg|thumb|right|150px|Saprolegnia - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
[[Image:Sporangiospores.jpg|thumb|right|150px|Sporangiospores - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath]]
 +
*Also known as mucormycosis, hyphomycosis and phycomycosis
 +
 
 +
*Caused by strains of ''Mucor, Absidia, Rhizopus'' and ''Mortierella''
 +
**''Mucor circinelloides''(rare), ''Rhizomucor pusillus'' and ''R. meihi''
 +
**''Absidia corymbifera'' often causes zygomycosis in cattle and pigs
 +
**''Rhizopus arrhizus, R. microsporus'' and ''R. rhizopodormis''
 +
**''Mortierella wolfi'' implicated in bovine abortion (mycotic placentitis), ''M. hygrophila'' in fowl and ''M.polycephala'' in cattle
 +
 
 +
*Occurs widely in nature
 +
 
 +
*Infection is by inhalation and ingestion
 +
 
 +
*Infects [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] of the [[Cardiorespiratory System - Anatomy & Physiology|respiratory]] and [[Alimentary - Anatomy & Physiology|alimentary tract]]
 +
**[[Lymph Nodes - Anatomy & Physiology|Lymph nodes]] enlarge and become caseous
 +
**Can cause [[Alimentary - Anatomy & Physiology#Stomach|stomach]] and [[Small Intestine - Anatomy & Physiology|intestinal]] ulcers
 +
 
 +
*Granulomatous lesions which can ulcerate
 +
 
 +
*Mostly localised lesions but can be generalised
 +
 
 +
*Pigs
 +
**Mediastinal and submandibular [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] lesions
 +
**Embolic tumours in the [[Liver - Anatomy & Physiology|liver]] and [[Lungs - Anatomy & Physiology|lungs]]
 +
**Can also be present in gastric ulcers
 +
 
 +
*Cattle
 +
**Bronchial, mesenteric and mediastinal [[Lymph Nodes - Anatomy & Physiology|lymph nodes]] lesions
 +
**Ulcers of the [[Nasal cavity - Anatomy & Physiology|nasal cavity]] and [[The Abomasum - Anatomy & Physiology|abomasum]] also occur
 +
**Often contaminate the [[Gestation -Placenta - Anatomy & Physiology|placenta]]
 +
 
 +
*Horses, dogs, cats, sheep, mink, guinea-pigs and mice can also be infected
 +
 
 +
*Microscopically:
 +
**Fragments of non-septate hyphae which are branched and coarse
 +
**''Rhizomucor'' produce a thick, grey mycelium and have short, black, spherical sporangia
 +
**''Mucor'' produce thick, colourless mycelium with no rhizoids. Globose spoangia with small spores are present and sporagiospores are simple or branched.
 +
**''Absidia'' resemble ''Rhizopus'' grossly
 +
**''Mortierella'' produce white, velvet colonies on Sabouraud's Dextrose and Blood agar
 +
 
 +
*Grows on Sabauraud's Dextrose agar
 +
**Common contaminants
 +
 
 +
*Treatment is with [[Antifungal Drugs#Polyene Antifungals|Amphotericin B]]
 +
**Surgery is also an option in treatment
 +
 
 +
==Further Links==
 +
 
 +
*[[Antifungal Drugs]]

Revision as of 19:12, 4 June 2009


 This article is still under construction.


Infectious agents and parasitesWikiBugs Banner.png
FUNGI



Adiaspiromycosis

  • Haplomycosis
  • Emmonsia crescens
    • Does not proliferate within the animal body
    • Each spore develops into a thick-walled spherule called an adiaspore
  • Chrysosporium parvum, C. crescens
  • Non-contageous, pulmonary mycosis
  • Worldwide
  • Found in soil
  • Affects burrowing rodents and small animals
  • Respiratory infection
  • Spetate hyphae with large numbers of small, round conidia either singly or in groups on the ends of the short conidiospores can be seen
  • Dimorphic
  • Grows on Sabauraud's Dextrose agar and Blood agar

Aspergillosis

Aspergillus cleistothecia - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Aspergillus in a swan - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Aspergillus in vivo - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Aspergillus sporing heads - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Canine nasal aspergillus radiograph - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Worldwide
  • Widely found in nature
    • Colonise a wide range of substrates under different environmental conditions
    • Abundant in hay, straw and grain which have heated during storage
  • Common laboratory contaminants
  • Pathogenic species include Aspergillus fumigatus, A. flavus, A. nidulans, A.niger and A. terreus
  • May cause primary or secondary disease
    • Infection may be acute, chronic or benign
  • Avians:
    • Diffuse infection of the air sacs
    • Diffuse pneumonic form
    • Nodular form involving the lungs
    • Spores are inhaled
    • Yellow nodules in the lungs and air sacs
    • The acute form usually affects young birds and is rapidly fatal (within 24-48 hours)
      • Signs include diarrhoea, listlessness, pyrexia, loss of appetite and loss of condition
      • Sometimes convulsions may occur
      • Resembles Pullorum disease
    • The chronic form usually occurs in adult birds and is sporadic, presenting with milder clinical signs
  • Cattle:
    • Infection can cause abortion and ocular infections
    • Infections involve the uterus, fetal membranes and fetal skin
    • Lesions are usually up to 2mm in diameter and contain asteroid bodies with a germinated spore in the centre
      • Acute infection causes miliary lesions
      • Chronic infections causes granulomatous and calcified lesions
  • Dogs, cats and sheep:
    • Infections occur, but infrequently
    • lungs and nasal cavity most usually affected
    • Disseminated form with granulomas and infarcts can occur in dogs
    • Pulmonary and intersitital forms can occur in cats
  • Grows on Sabauraud's Dextrose and Blood agar
    • White colonies intitially which turn green, then dark green, flat and velvety
    • Colony colour varies with species
  • Also grows on Czapek-Dox agar and 2% malt extract agar supplemented with antibacterial antibiotics
  • Microscopically:
    • Conidiophores with large terminal vesicles (only visible in the lungs and air sacs where there is access to oxygen)
      • Vesicle shape varies depending on the species
    • Is a common contaminant so repeated tests should be done for a definitive diagnosis
  • Serology:
    • Gel immunodiffusion for canine nasal asper

Blastomycosis

  • North America
    • Most common in the North-Central and South-Eastern states
  • Caused by Blastomyces dermatitidis
  • Widespread in soil
  • Respiratory infection
  • Lesions start in the lungs
    • Haematogenous dissemination
    • Can be found in lesions in the eyes, brain, bones and genitalia
    • Fatal if not treated
  • Lesions are also found on the skin
  • These may ulcerate
  • Granulomatous nodules
  • Affects mainly dogs (and humans)
    • Can affect cats, horses, dolphins, ferrets and sealions but is rare in these species
  • Microscopically:
    • Large, spherical, thick-walled cells
    • Single buds connected to a mother cell by a wide base
    • Double contoured effect of cells
  • Grows on Sabauraud's Dextrose and Blood agar
    • On Sabauraud's Dextrose colonies appear moist and grey with a white cotton-like mycelium which turns tan, brown and then black
      • Septate hyphae
      • Small, oval/pyriform conidia
      • Older cultures have thickened walls
    • On Blood agar colonies are creamy in colour, waxy and wrinkled
      • Thick-walled budding yeast cells can be seen
  • Diagnosis:
    • Complement fixation test
    • Falling antibody titres indicate a poor prognosis
    • ELISA and counterimmunoelectrophoresis can also be used

Coccidioidomycosis

Coccidioidomycosis spherule histopathology - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Coccidioides immitis
  • Ocurs in the soil
    • Respiratory infections
    • Most commonly seen following dust storms
  • Occurs in arid regions
    • E.g. South West USA and Mexico
  • Non-contageous, systemic mycosis
  • Affects dogs, cattle, sheep and humans
  • Mainly affects the lungs
    • Dissemination can occur to other organs
  • Causes nodule or granuloma formation
    • Localised
    • Gross lesions resemble Tb in cattle as are usually seen in the bronchial and mediastinal lymph nodes and occasionally lungs
    • Dissemination can occur, especially in primates and dogs, to the lungs, liver, spleen, brain and bones
  • Thick-walled spherules in tissue
    • Large sporangia burst leaving 'ghost' spherules
  • Saprophytic phase consists of coarse, septate, branching hyphae which fragment into thick-walled, barrel-shaped arthrospores which alternate with empty cells
    • Stained by Lactose Phenol Cotton Blue
  • Grows on Sabouraud's Dextrose agar and Blood agar
    • Flat, moist colonies which develop a coarse, cotton-like aerial mycelium which varies from white to brown in colour
  • Complement fixation test, latex agglutination and immunodiffusion tests can all be used
    • A positive skin test indicates exposure

Entomophthoromycisus

  • Basidiobolmycosis
  • Caused by Basidiobolus and Conidiobulus fungi
  • Causes ulcerative granulomas in subcutaneous tissue
  • Affects the oral and nasal mucous membranes
  • Basidiobolus causes large lesions which may involve skin on the head, neck and chest
  • Produce flat, waxy colonies which become white and fizzy over time
  • Microscopically:
    • Septate hyphae

Histoplasmosis

  • Histoplasmosis in a canine spleen

    Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Histoplasma capsulatum
  • Non-contageous, systemic mycosis
  • Commonly pulmonary infections occur
    • Other organs can be involved
    • Involves the reticuloendothelial system
    • Intestinal form can also occur
  • Acute and chronic disease can occur
  • Endemic to the USA
    • Isolated cases have been reported in Europe
  • Respiratory infection
    • Infection via ingestion can also occur
  • Affects dogs, cats, cattle, horses and humans
  • Found in soil contaminated by bird droppings, decaying vegetation and in caves inhabited by bats

  • Histoplasmosis lesions in lungs

    Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Fine, branching, septate hyphae with smooth-walled pyriform to spherical microconidia and large, thick-walled tuberculate macroconidia on simple conidiophores
  • Dimorphic fungi
  • Hard to demonstrate in smears as the organisms is very small
    • Stain with Giemsa or Wright and examine under oil immersion lens
  • Present intracellularly in macrophages as oval yeast cells with few buds
    • Clear halo is seen around the darker staining central material
  • Grows on Sabouraud's Dextrose agar
    • Creamy white colonies, turning tan coloured and then brown
  • Also grows on Blood agar
    • Small, white yeast-like colonies
  • Test using immunodiffusion, complement fixation and counterimmunoelectrophoresis
    • Skin test of little value as it only indicates exposure
  • The prognosis is poor in acute and disseminated cases


  • Histoplasmosis in a canine spleen using silver stain

    Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

  • Histoplasmosis phagocyte

    Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

  • Histoplasmosis tuberculate chlamydospores

    Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

Zygomycosis

Mucor liver - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Mucor mould on the ruminal surface- Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Saprolegnia salmon - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Saprolegnia - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Sporangiospores - Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Also known as mucormycosis, hyphomycosis and phycomycosis
  • Caused by strains of Mucor, Absidia, Rhizopus and Mortierella
    • Mucor circinelloides(rare), Rhizomucor pusillus and R. meihi
    • Absidia corymbifera often causes zygomycosis in cattle and pigs
    • Rhizopus arrhizus, R. microsporus and R. rhizopodormis
    • Mortierella wolfi implicated in bovine abortion (mycotic placentitis), M. hygrophila in fowl and M.polycephala in cattle
  • Occurs widely in nature
  • Infection is by inhalation and ingestion
  • Granulomatous lesions which can ulcerate
  • Mostly localised lesions but can be generalised
  • Pigs
    • Mediastinal and submandibular lymph nodes lesions
    • Embolic tumours in the liver and lungs
    • Can also be present in gastric ulcers
  • Horses, dogs, cats, sheep, mink, guinea-pigs and mice can also be infected
  • Microscopically:
    • Fragments of non-septate hyphae which are branched and coarse
    • Rhizomucor produce a thick, grey mycelium and have short, black, spherical sporangia
    • Mucor produce thick, colourless mycelium with no rhizoids. Globose spoangia with small spores are present and sporagiospores are simple or branched.
    • Absidia resemble Rhizopus grossly
    • Mortierella produce white, velvet colonies on Sabouraud's Dextrose and Blood agar
  • Grows on Sabauraud's Dextrose agar
    • Common contaminants
  • Treatment is with Amphotericin B
    • Surgery is also an option in treatment

Further Links

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