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Aspergillosis
Introduction
- Two forms of aspergillosis are reported most commonly in the cat (upper respiratory tract aspergillosis (URTA), disseminated invasive aspergillosis (DIA)).
- URTA is an emerging mycosis of cats worldwide, and can be divided into two anatomic forms: sino-nasal aspergillosis (SNA) where disease is restricted to the sino-nasal cavity, and sino-orbital aspergillosis (SOA), the more common and aggressive form, with additional orbital involvement.
- Cause: Aspergillus spp (most commonly Aspergillus felis, A. fumigatus and A. niger in URTA. The Aspergillus spp that cause DIA are largely unknown because most cases have been diagnosed at post-mortem from histologic findings only. Infection by spores (condia), usually inhaled.
- Signs: SNA - sneezing, nasal discharge, epistaxis, stertor; SOA - exophthalmos (usually unilateral), 3rd eyelid prolapse, exposure keratitis, conjunctival hyperemia, oral mass or ulcer in ipsilateral pterygopalatine fossa, paranasal soft-tissue swelling, nasal signs may not be present at time of presentation for a retrobulbar mass; disseminated disease - vomiting, diarrhea, lethargy, cachexia, renal failure, and respiratory disease.
- Diagnosis: URTA - combination of serology (ELISA to detect Aspergillosis-specific IgG), diagnostic imaging findings, visualization of fungal plaques on endoscopy, cytological or histological detection of hyphae in tissue biopsies, fungal culture. PCR and sequencing is required for correct idenitifcation to species level in most cases; most frequently made post-mortem with disseminated disease.
Presenting signs
- SNA:
- Nasal discharge Nasal discharge (serous to mucopurulent).
- Sneezing Sneezing.
- Stertor.
- Ipsilateral mandibular lymph node enlargement.
- Epistaxis Epistaxis (30% of cases).
- Fever.
- Discharging sinus or soft-tissue mass involving the nasal bone/frontal sinus.
- SOA:
- Nasal signs (concurrent or within previous 6 months).
- Unilateral exophthalmos with dorsolateral deviation of the globe.
- Ipsilateral conjunctival hyperemia/3rd eyelid prolapse.
- Ipsilateral corneal ulceration.
- Oral mass/ulcer in ipsilateral pterygopalatine fossa.
- Paranasal soft-tissue swelling or discharging sinus or mass.
- Mandibular lymph node enlargement.
- CNS signs (15%) - seizures, blindness.
- Disseminated disease:
- Vomiting, diarrhea.
- Depression, weight loss, fever.
- Dyspnea and cough.
- Hematuria, polyuria.
- CNS signs.
- Lymphadenopathy Lymphadenopathy.
Geographic incidence
- Worldwide.
Age predisposition
- Disease usually occurs in young to middle-aged cats (median 6.5 y) but can occur in cats of any age.
Pathogenesis
Etiology
- SNA: usually Aspergillus fumigatus Aspergillus fumigatus or A. niger, occasionally other species in Aspergillosis fumigatus complex, eg A. lentulus.
- SOA: usually Aspergillus felis, A. udagawae, or other species in A. fumigatus complex.
- Disseminated disease: largely unknown. A. fumigatus was cultured from two cats with mycotic pneumonia, and A. nidulans from one cat with mycotic cystitis.
Predisposing factors
General
- Access to saprophytic fungi in soil and decaying vegetation. Fungal conidia have also been detected in indoor air samples.
- URTA: generally systemically immunocompetent (FIV, FeLV negative), brachycephalic pure-bred cats, especially Persian/Himalayan account for over a third of all cases; disease occasionally occurs in association with nasal neoplasia Nasal cavity: neoplasia or foreign bodies.
- Disseminated disease: immunosuppression from panleukopenia virus Feline panleucopenia virus disease, FeLV Feline leukemia virus disease, FIV Feline immunodeficiency virus disease , FIP Feline infectious peritonitis, administration of corticosteroids.
Pathophysiology
URT aspergillosis
- Inhalation of fungal spores → local infection of the nasal cavity and paranasal sinuses.
- Infection can be non-invasive, similar to canine SNA, where fungal colonies maintain close contact with nasal mucosa but fungal hyphae do not penetrate into cells. Such infections remain restricted to the sino-nasal cavity. SOA is always invasive, where fungal hyphae are found within tissues.
Disseminated aspergillosis
- Inhalation of fungal spores → association with immunocompromised state → pulmonary infection → hematogenous dissemination to eye, kidneys, intestines, liver, spleen, lymph nodes, brain.
Epidemiology
- Since the saprophytic fungi that cause aspergillosis are disseminated widely in nature, both URTA and DIA occur in cats worldwide → inhalation of fungal spores.
- Disease usually occurs in young to middle-aged cats (median 6.5 y) but can occur in cats of any age.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Barrs V R, Talbot J J (2014) Feline aspergillosis. Vet Clin North Am Sm Anim Pract 44 (1), 51-73 PubMed.
- Barrs V R, Beatty J A, Dhand N K et al (2014) Computed tomographic features of feline sino-nasal and sino-orbital aspergillosis. Vet J 201 (2), 215-22 PubMed.
- Barrs V R, van Doorn T M, Houbraken J et al (2013) Apergillus felis sp. nov., an emerging agent of invasvie aspergillosis in humans, cats and dogs. PLoS One 8 (6), e64871 PubMed.
- Hartmann K, Lloret A, Pennisi M G et al (2013) Aspergillosis in Cats: ABCD guidelines on preventions and management. J Feline Med Surg 15 (7), 605-610 PubMed.
- Barrs V R, Halliday C, Martin P et al (2012) Sinonasal and sino-orbital aspergillosis in 23 cats: aetiology, clinicopathologic features and treatment outcomes. Vet J 191 (1), 58-64 PubMed.
Other sources of information
- Sykes J E (2014) Aspergillosis. In: Sykes J E Canine and Feline Infectious diseases. Elsevier, p 633.