Systemic Mycoses

From WikiVet English
Jump to navigation Jump to search



Infectious agents and parasitesWikiBugs Banner.png
FUNGI



Adiaspiromycosis


Aspergillosis


Blastomycosis


Coccidioidomycosis

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

  • 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
  • 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


Zygomycosis

  • 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