Opportunistic Environmental Fungi Flashcards
What is the ecology of Aspergillus spp.?
- Common soil inhabitants
- decomposing organic matter
- Spores present in dust and air.
Describe Invasive Aspergillosis.
- Spores inhaled into nasal passages or lungs – if not eliminated by phagocytic cells, then…
- Development of germ tube (1-2 days) – sets out hyphae looking for food source – stimulates host inflammatory reaction and see buildup of exudate. Buildup of fluid as part of the inflammatory response. If overcome host reaction, then…
- Hyphae grow – host tries to limit growth. Fibrous capsule develops around infected area. If overcome host defenses, then…
- Hyphae invade surrounding tissues. If invade blood vessels, then…
- May see widespread dissemination of fungus.
Describe Apergilloma
- A fungus ball that may calcify
- Non-invasive aspergillosis
- Cavitated areas of lung colonized.
- Isolated pocket of aspergillus can be invasive as it can cause a lot of bleeding if close to vasculature.
Describe Allergic Aspergillosis
Hypersensitivity reaction.
Heaves/COPD in horses.
What is the clinical presentation of Canine nasal aspergillosis?
Common in dolichocephalic dog breeds (long nose). Young to middle aged dogs - scavenging. Could be immunocompromised. Often unilateral presentation. Hyphae invade and destroy nasal tissue- nasal passages, turbinates and paranasal sinuses. Nasal discharge and epistaxis. Can occasionally see fungal plaque.
What is the treatment of Canine nasal aspergillosis?
1) Flush nasal chambers and frontal sinuses (need to get everything out)
2) Systemic treatment for 6-8 weeks
3) May need surgery in some cases.
What is the clinical presentation of disseminated canine aspergillosis?
Osteomyelitis. Severe muscle wasting. German Shepherds predisposed.
What is the treatment of disseminated canine aspergillosis?
Antifungal drugs but poor prognosis
What is the clinical presentation of equine guttural pouch aspergillosis?
Unilateral.
Plaque like lesions in mucosa of pouch wall (endoscope).
Plaque very close to internal carotid artery - can go systemic.
Muco-purulent nasal discharge.
Epistaxis (nosebleed)
Neurological signs- dysphagia (inability to swallow), laryngeal hemiplegia- whistle/roar, tongue atrophy. Laryngeal deformation due to enlarged guttural pouch.
Post-auricular swelling.
Rare- keratomycosis (fungal infection of cornea), abortion, pulmonary infection, enteritis in foals.
What is the treatment of equine guttural pouch aspergillosis?
1) Oral or systemic antifungal drugs - potential toxicity, high costs, often ineffective.
2) Infusion of antifungal agents into pouch- endoscope.
3) Surgical occlusion of arteries above and below lesion, coil embolization.
What is the treatment of avian aspergillosis?
Difficult treatment - oral or nebulized antifungals. Surgery.
What is the ecology of Cryptococcus neoformans v. neoformans?
Reservoir- avian droppings and contaminated soil. Pigeons may excrete for months, do not necessarily show signs of disease, yeast survives in faeces for up to 12 months.
What is the ecology of Cryptococcus neoformans v. gattii?
Timber associated- decaying forest red gum trees (Eucalyptus spp.). Associated with meningitis in humans. Found in AUS, SE Asia, South America, Africa and countries that have imported gum trees.
Describe the clinical presentation of feline cryptococcosis.
Young to middle aged, outdoor cats.
Risk not increased with FIV/FeLV but may be harder to treat (different age group).
Nasal signs- flesh coloured, polyp like granulomas in nasal cavity. Few cases are cutaneous - lesions typically occurring on the head, face and neck. Pulmonary signs rare.
What are the limitations of treatments for feline cryptococcosis?
Can take months-years and does not preclude relapse/reinfection/asymptomatic colonization of nasal cavity. Toxicity can be substantial.
Flucytosine resistance can develop.
