MYCOZOONOSES

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MYCOZOONOSES

• Mycotic agents with zoonotic potential
• Systemic (deep) fungal
• Cryptococcus neoformans
• Blastomyces dermatidis
• Histoplasmosis
• Dermatophytes
• Microsporum canis
• Trichophyton spp.

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CRYPTOCOCCOSIS

• Other names European blastomycosis, torulosis
• Agent Cryptococcus neoforman
• Two subspecies neoformans, gattii
• A yeast-like organism causing deep mycosis
• Most common potentially fatal fungal infection in
  AIDS patients

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CRYPTOCOCCOSIS

• Microbiological features
• Globose yeast organism
• Readily identified from tissue
• Growth in Sabouraud or Brain heart infusion agar
  within 2-5 days

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CRYPTOCOCCOSIS

• Microbiological features - india ink preparation
  of CSF showing encapsulated yeast

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CRYPTOCOCCOSIS

• Epidemiology
• Occurrence sporadic cases worldwide
• up to 10 of AIDS patients in US and Western
  Europe
• up to 30 of AIDS patients in Africa
• Reservoir saprophyte, especially in pigeon
  nesting/roosting areas var. gattii isolated from
  Eucalyptus trees
• Transmission inhalation

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CRYPTOCOCCOSIS

• Clinical features
• Incubation period unknown
• Acute pulmonary disease - seen primarily in
  non-cmopromised patients good prognosis
• Chronic disease - relapsing/remitting cycle
  usually eventually fatal
• CNS disease usually preceeded by pulmonary
  disease fatal unless treated early

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CRYPTOCOCCOSIS

• Clinical features
• Diagnosis
• histopathological changes in tissue
• isolation techniques
• Antigen tests may be of use
• Disease in animals usually disseminated form,
  with primary manifestation of meningitis
• Pigeons do not show symptoms

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CRYPTOCOCCOSIS

• Diagnosis - direct examination of brain tissue

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CRYPTOCOCCOSIS

• Diagnosis - direct examination of brain tissue

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BLASTOMYCOSIS

• Other disease names Gilchrists disease,
  Chicago disease
• Agent Blastomyces dermatitidis
• A dimorphic fungus

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BLASTOMYCOSIS

• Microbiological features
• Grows as a mold at room temperature (25ºC) and a
  yeast in tissue (37ºC)
• Yeast form direct microscopic exam of tissue
  shows globus, thick walled yeast-like organisms
  called blastoconidium
• Mould form growth on Sabouraud agar after 4
  weeks mycelium similar to other fungi

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BLASTOMYCOSIS

• Microbiological features - mycelial phase

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BLASTOMYCOSIS

• Microbiological features - tissue phase

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BLASTOMYCOSIS

• Epidemiologic features
• Reservoir soil
• Mode of transmission usually direct contact
  with soil or aerosols containing fungal conidia
• Occurrence sporadic disease in US (Ohio and
  Mississippi River valley), Canada, Africa
• More prevalent in males 40-60 years of age

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BLASTOMYCOSIS

• Clinical features
• May be benign or self-limiting infection
• Pulmonary form
• acute suppurative and granulomatous inflammation
• mild cough, chest pain, weight loss, low grade
  fever
• Cutaneous form
• skin erythematous rash on face and extremities,
  can become ulcerative and crusty

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BLASTOMYCOSIS

• Clinical features
• If untreated, disseminated or chronic pulmonary
  form leads to progressive debilitation and
  eventually death
• Affects animals, especially dogs, causing
  respiratory disease

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MYCOTIC ZOONOSES

• Histoplasmosis
• Coccidioidomycosis
• Cryptococcosis
• Blastomycosis
• Dermatophytosis

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MYCOTIC ZOONOSES

• Mycosis - a disease caused by a fungus
• Fungus - a eukaryotic microorganism that falls in
  one of two primary groups, either mould or yeast
• Estimated 1.5 million species of fungi,
  approximately 400 are pathogenic to man or
  animals

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HISTOPLASMOSIS

• Other disease names Darlings disease, cavern
  disease
• Agent Histoplasma capsulatum var. capsulatum
  H. capsulatum var. duboisii
• A systemic mycosis caused by a dimorphic fungus

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HISTOPLASMOSIS

• Microbiological features
• Grows as a mold at room temperature (25ºC) and a
  yeast in tissue (37ºC)
• Saprophytic (mycelial) phase - mould form that
  may take up to 12 weeks for growth on media
  mycelia of two varities similar
• Parasitic (yeast) phase - yeast-like cells of
  var. capsulatum much larger (7-15?) than var.
  duboisii (2-5?)

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HISTOPLASMOSIS

• Microbiological features

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HISTOPLASMOSIS

• Electron micrograph of H. capsulatum spore

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HISTOPLASMOSIS

• Microbiological features

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HISTOPLASMOSIS

• Microbiological features

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HISTOPLASMOSIS

• Epidemiologic features
• Reservoir
• soil with undisturbed bird droppings, especially
  caves (bats) and roosts (starlings, pigeons,
  blackbirds, chickens)
• certain species of bats become infected with
  organism and disseminate fungus through droppings
• Mode of transmission usually direct contact
  with soil or aerosols containing fungal
  microconidia

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HISTOPLASMOSIS

• Epidemiologic features
• Occurrence
• var. capsulatum - worldwide
• var. duboisii - Africa
• distribution in soil not uniform, dependant on
  temperature, humidity, and other factors
• in US, found predominantly in rural areas in
  Missouri, Mississippi, and Ohio River valleys
• prevalence of exposure may be as high as 80
  based on skin test

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HISTOPLASMOSIS

• Occurrence in US

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HISTOPLASMOSIS

• Clinical features
• Incubation period 5-18 days
• Prior to AIDS epidemic, gt 90 of cases were
  inapparent or benign
• Varying severity ranging from mild respiratory to
  death
• All stages may mimic TB
• may also occur in animals

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HISTOPLASMOSIS

• Clinical features
• Primary forms of disease
• Pulmonary
• benign respiratory - flu-like symptoms
• chronic respiratory disease with cavitation like
  TB occurs particularly in older men with
  underlying emphysema

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HISTOPLASMOSIS

• Clinical features - pulmonary

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HISTOPLASMOSIS

• Clinical features
• Primary forms of disease
• Disseminated
• chronic disseminated disease - low grade fever,
  weight loss, focal (liver, spleen, heart, GI
  tract) fatal if untreated
• acute fulminating disease (systemic) - fever,
  multiple organ involvement, rapid course, fatal
  without treatment

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HISTOPLASMOSIS

• Clinical features
• Ocular histoplasmosis syndrome (OHS)
• leading cause of vision loss in 20-40 yr olds
  (US)
• spores spread from lungs to eyes, lodging in
  choroid layer (vessels supplying retina)
• if untreated, scar tissue and abnormal leakage of
  blood and fluid replace macula, thus blocking
  passage of visual message to brain
• treatment - laser surgery (photocoagulation) not
  curative, only prevents further damage

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HISTOPLASMOSIS

• Clinical features
• Diagnosis
• Histopathology
• acute phase H. capsulatum present in
  histiocytes and reticuloendothelial cells
• chronic phase coin lesions - well developed
  granulomatous lesions from pulmonary tissue
  (nodules)

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HISTOPLASMOSIS

• Clinical features
• Diagnosis
• Laboratory
• culture - mould to yeast conversion for
  confirmation incubate (30ºC lt 12 wks)
• direct examination of tissue with special stains
  such as Geimsa, PAS - difficult
• serology - immunodiffusion tests and CF titer,
  but unreliable due to cross-reactivity and false
  negatives

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HISTOPLASMOSIS

• Diagnosis
• Antigen detection assay from Histoplasmosis
  Reference Laboratory (Indiana University)
• rapid diagnosis
• measurement of antigen in urine or serum offers
  highest sensitivity for serious infection
• specificity - 98
• sensitivity - 92 for disseminated form
• useful for monitoring therapy

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HISTOPLASMOSIS

• Clinical features
• Treatment
• Amphotericin B (IV) - drug of choice
• Oral ketaconizole

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DERMATOPHYTOSIS

• Agents zoopholic species of dermatophytes
• Microsporum canis
• Trichophyton mentagrophytes
• Trichophyton equinum
• Trichophyton verrucosum

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DERMATOPHYTOSIS

• Epidemiology
• Occurrence ubiquitous worldwide
• M. canis very common in dogs and cats in both
  rural and urban settings
• Trichophyton spp common in rural settings where
  cattle, horses, rodents, and wild animal are
  infected
• Reservoir for zoophillic organisms--cats, dogs,
  horses, cattle, rodents, wild animals
• Transmission direct skin-skin or indirect with
  inanimate objects (tack, saddle, brush, bedding)

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DERMATOPHYTOSIS

• Clinical
• Incubation period 4-14 days depending on area
  affected nail fungal infections may be longer
• Mycotic disease of keratinized structures
• Lesions regardless of location start as papule,
  spreads forming crusty circular lesion with
  alopecia

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DERMATOPHYTOSIS

• Clinical
• Dermatophytosis (ringworm) in humans named by
  location
• tinea capitis - ringworm of scalp
• tinea barbae - ringworm of beard
• tinea cruris - ringworm of groin/perianal (jock
  itch)
• tinea corporis - ringworm of body
• tinea pedis - ringworm of foot (athletes foot)
• tinea unguium - ringworm of nails (onchomycosis)

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DERMATOPHYTOSIS

• Clinical
• Diagnosis
• microscopic exam of ascrapings from lesions
  reveal branching elements
• ectothrix (outside hair) - Microsporum spp.
• endothrix (inside hair) - Trichophyton spp.
• UV light exam reveals immunoflouresence
  (Microsporum spp.)
• Culture recommended, but growth slow

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DERMATOPHYTOSIS

• Clinical
• Treatment
• topical fungicides - powder, cream, solution
• oral fungicides - especially for refractory
  infections and onchomycosis long term treatment
  (4-6 months)
• griseofulvin
• fluconazole
• itraconazole
• terbinafine

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DERMATOPHYTOSIS

• Microsporum canis

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DERMATOPHYTOSIS

• Trichophyton mentagrophytes

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DERMATOPHYTOSIS

• Trichophyton verrucosum

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DERMATOPHYTOSIS