Difference between revisions of "Subcutaneous Mycoses"

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==Chromomycosis==
+
[[Chromomycosis]]
  
*Also called Phaeohyphomycosis
 
  
*Opportunistic
 
 
*Infects horses, dogs and humans
 
**Found in wounds and abrasions
 
 
*Caused by [[Dermatophytosis|dematiaceous fungi]]
 
**''Dactylaria gallopava, Exophiala pisciphila, E. salmonis, Scolecobasidium humicola, S. tshawytschae, Drechslera, Exophilia jeanselmeri, E. verrucosa, Fonsecaea pelrosoi''
 
 
*Nodular and ulcerating lesions of the skin on the feet, legs and occasionally eyes (in turkeys)
 
**Regional granulomatous lymphadenitis
 
 
*Single cells or clusters, spherical and thick-walled
 
*Brown pigmented fungal elements
 
 
*Multiply by cross-wall formation or splitting (not budding)
 
 
*Grows on Sabauraud's Dextrose agar ar room temperature
 
**Slow growth
 
**Takes one month
 
 
*For further information, see [[Dermatophytosis|dematiaceous fungi]]
 
  
 
==Epizootic Lymphangitis==
 
==Epizootic Lymphangitis==

Revision as of 13:33, 29 April 2010



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FUNGI



Chromoblastomycosis


Chromomycosis


Epizootic Lymphangitis

  • Histoplasma capsulatum var. farciminosum
    • Similar to H. capsulatum
  • Occurs in horses, donkeys and mules
  • 90% occurs in horses
  • Occurs in Europe, Africa and Asia
    • Eradicated from the UK but is still under the notifiable Diseases of Animals Act
  • Chronic disease
  • Highly contageous
    • Spread by direct contact or indirect, e.g. through infected grooming equipment, biting flies
  • Once established in a population it is very difficult to eradicate
    • Long incubation peroid
    • New cases can develop weeks or months after the infection appears to have been eradicated
  • Causes ulcerative, nodular lesions
    • Dissemination occurs
    • Pulmonary disease can occur
    • Ulcers rupture, discharging blood-stained pus for several weeks
  • Oval or pear shaped cells
    • Double contoured
    • Dimorphic
      • Grows in the yeast phase at 37°C and in the mycelial phase at room temperature
    • Growth is slow, taking up to 8 weeks
    • At room temperature, thick-walled chlamydospores can be seen
    • Orgnaisms can usually be seen in swollen leucocytes
  • Can be stained using Gram, Giemsa, H & E and 10% Methylene Blue followed by Carbol Fuchsin
  • Enzyme-linked immunosorbant assay can be used to detect the fungi
  • Life-long immunity follows recovery from infection
  • Treatment included potassium iodide, hamycin and Amphotericin B
    • Vaccination has also proven to be effective
    • Injection of hyperimmune serum around skin lesions has been proven to be effective

Eumycotic Mycetoma

  • Pseudoallescheria boydii, Curvularia geniculata, Cochliobolus spicifer, Helminthosporium spp.
  • Lives in soil
  • Enters the body via wounds
  • Granulomatous abscesses
  • Microcolonies can be seen grossly in exudate or lesions
    • Grains or granules
    • Brown or black embedded in granulation tissue
    • Small, irregularly shaped
  • Infrequent infections of dogs, cats, cattle and horses
  • Usually affect the extremities
    • Can infect the nasal mucosa
      • E.g. Bovine nasal granuloma
    • Can also infect the peritoneum and skin
  • Microscopically:
    • Grains of maduromycosis with wide mycelia (compared to actinomycotic granules)
    • Chlamydospores present
  • Grows on Sabauraud's Dextrose agar
    • Slow
    • Takes 2-3 weeks

Hyphomycosis

  • Hyphomyces destruens
  • Opportunistic infection
    • Associated with trauma
  • Rare
  • Caused by Penicillium, Beauveria, Acremonium, Fusarium, Paecilomyces
  • Infects both animals and humans
    • Mainly affects horses
  • Tropical and semi-tropical countries
  • Progressive disease causing granulating and ulcerating lesions on the legs and lower body
    • Lesions grow rapidly
    • Cause extreme debility
  • Occurs in water
    • Most often seen in ponies with access to ponds
  • Chemotactically attracted to horse hair
  • Does not respond well to treatment
    • Radical surgical excision the best method
    • Experiemental vaccination treatment is currently underway and has shown promising results

Pythiosis

  • Causes Mycotic Swamp Fever
  • Also called phycomycosis
  • Occurs in the USA, Australia, New Guinea, India, Brazil, Colombia, Japan, Costa Rica and Indonesia
  • Pythium insidiosum
  • Granulomatous infection
    • Necrosis and fistulous tracts
    • Yellow lesions
  • Branching, separated fungi
  • Progressive (rather than systemic) disease
  • Surgery is needed

Rhinosporidiosis

  • Rhinosporidium seeberi
  • Lives in water
  • Causes a chronic, benign disease
  • Affects cattle, mules, horses, dogs and humans
  • Causes polyps on the nasal and ocular mucous membranes
    • Over 90% of cases affecting the nasal mucous membranes affects male animals
  • Occurs most frequently in tropical countries
    • Also common in the USA
  • Large sporangia can be seen on wet mounts
    • Endospores visible
    • Sporangia develop into small, globose spores
  • Treatment is by surgical excision

Sporotrichosis

Sporotrichosis in a horse -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Sporotrichosis cigar shaped cells -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Sporothrix schenckii
  • Occurs in soil, wood and vegetation
    • Saprophyte of both decaying and healthy vegetation
  • Worldwide
  • Exogenous infections through wounds
  • Sporadic infections
  • Non-contageous
  • Causes subcutaneous nodules or granulomas
    • Nodules ulcerate discharging pus
  • The bones and viscera can be involved which terminates in mortality
    • This is rare
    • Reported in dogs and horses
  • Affects dogs, horses, cats, monkeys, mules, camels, donkeys, cattle, fowl and rodents
    • Most commonly seen in horses as an ascending lymphocutaneous infection of the legs
    • Can be confused with epizootic lymphangitis in horses
  • Single cell, cigar shaped
    • Usually found within neutrophils
    • Yeast cell clusters with peripheral eosinophilic rays can be seen in tissue sections
  • Stained using PAS, Gram stain (positive), fluorescent antibody and Calcofluor White
  • Latex agglutination and immunodiffusion serology can be performed
  • Grows on Blood agar and Sabouraud's Dextrose agar in one to three weeks
    • At 37°C:
      • Colonies are smooth, cream to tan coloured and soft
      • No mycelium can be seen
    • At 25°C to 27°C:
      • Colonies turn from white and soft to tan to brown to black
      • Leathery, wrinkled and coarse
      • Mycelium can be seen as branching septate hyphae
      • Conidiospores can also be seen

Further Links