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Aspergillosis in Avian Wildlife

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Title: Aspergillosis in Avian Wildlife


1
Aspergillosis in Avian Wildlife
  • Aggressive Diagnostics and Treatment
  • Dont wait another day

2
Avian Respiratory Anatomy
  • Complete tracheal rings
  • Prevents collapsing of trachea at high altitudes
  • Strangulation during handling difficult
  • Tracheal bifurcation cranial and dorsal to heart
    base
  • Syrinx cranial to bifurcation
  • Primary bronchus enters lung lobe, divides into
    secondary bronchus, then parabronchus
  • Air flows from parabronchus to atria to air
    capillaries
  • Oxygen and carbon dioxide exchange

3
Air Sac Anatomy
  • Four sets of air sacs
  • Cervical
  • Cranial thoracic
  • Caudal thoracic
  • Abdominal
  • Varies with species
  • Air sac membranes very thin
  • No gas exchange in air sacs
  • Very little vasculature to air sacs

4
Avian Respiratory Physiology
  • Every air capillary connected to adjoining air
    capillary
  • Air flow is continuous and uni-directional
    (unlike mammals)
  • Air cannot be trapped in lung therefore no
    pulmonary emphysema
  • Lungs do not expand with inspiration
  • Two breaths for air to circulate through
    respiratory system
  • 1st inspiration- air shunted to caudal thoracic
    and abdominal air sacs
  • Expiration- air moves from air sacs through lungs
  • 2nd inspiration- air in lungs enters cranial
    thoracic and cervical air sacs

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Aspergillus spp.
  • Ubiquitous, opportunistic fungus
  • Thick walled, septate, branching
  • Grows readily in moist, warm environments
  • Found in soil, wood shavings, corn cob bedding,
    seed hulls, straw, etc.
  • World-wide distribution
  • Species
  • Most common A. fumigatus, A. niger, A. flavus
  • Less common A. glaucus, A. oryzae, A. nidulans

11
Who is susceptible?
  • Immuno-compromised animals
  • Young, old, stressed (wildlife in captivity)
  • Raptors
  • Gyrfalcons, Goshawks, Bald eagles, Red-tailed
    hawks, Owls
  • Most common cause of death in captive and
    recently captured free-ranging birds of prey
  • Most important non-traumatic disease of birds of
    prey
  • Aquatic birds
  • Swans, geese, diving and shore birds
  • Game birds
  • Pheasants, wild turkeys
  • Parrots
  • African Greys, Pionus, BF amazons, mynah birds

12
Some Susceptible Species
13
Pathogenesis
  • Forms- depend on chronicity, organs affected,
    number of spores exposed and host immune system
  • Focal or localized lesions
  • Trachea, bronchus, sinus, nasal cavity, skin
  • Systemic infections- fungal hyphae are invasive,
    erode through body barriers and blood vessels
  • Acute
  • Chronic

14
Acute Aspergillosis
  • Overwhelming dose of fungal spores
  • Clinical course over a few days
  • Birds die in good body condition
  • Invasive to pulmonary tissue with aerogenous and
    hematogenous dissemination
  • Common site syrinx and tracheal bifurcation
  • Turbulence of air forces spores drop out of air
    column
  • Narrowing of trachea predisposes to blockage of
    necrotic debris

15
Chronic Aspergillosis
  • Low dose, granulation formation
  • Slowly progressive, usually gt 3 weeks
  • Exposure to low level of persistent spores
  • Usually immuno-compromised individuals
  • Recent imports, injured, migratory, long-term
    antibiotics therapy, inadequate nutrition,
    CAPTIVE WILDLIFE
  • Respiratory disease usually extensive before
    clinical signs apparent
  • Hypovitaminosis A gt squamous metaplasia gt spore
    invasion

16
Clinical Signs
  • Respiratory-
  • Coughing, wheezing, change or loss in phonation,
    dyspnea, increased RR, open-mouth breathing,
    depression, emaciation, tail bobbing
  • Gastro-Intestinal
  • Biliverdinuria, diarrhea, regurgitation, anorexia
  • Neurologic
  • Posterior paresis, lameness
  • /- ascites due to cardiogenic disease

17
Focal Aspergillosis
18
Diagnosis
  • Non-specific
  • Hematology
  • WBC- heterophilia, monocytosis, lymphopenia
  • RBC- non-regenerative anemia
  • Serum chemistries
  • SGOT (liver)- elevated
  • CPK (muscle) elevated
  • Hypoalbumenemia
  • Hyperproteinemia and hypergammaglobulinemia
  • Radiography

19
Radiology
  • Whole body
  • Hyper-inflated air sacs, aerophagia, air in
    cloaca
  • Focal densities in lungs or air sacs
  • Thickened air sac walls
  • Lateral view
  • Syringeal or caudal thoracic air sac lesions
  • Ventro-dorsal view
  • Caudal thoracic and abdominal air sac lesions
  • Head
  • Nasal aspergillosis- turbinate destruction

20
Other Non-specific Tests
  • Serology
  • Ag titers
  • Ab titers
  • PEP (protein electrophoresis)
  • Separation of serum proteins utilizing an
    electric field and gel
  • 5 protein fractions
  • Increase in acute phase proteins (alpha 1 2,
    beta)
  • Increase in chronic phase proteins (gamma
    globulins)
  • Increase in total protein and globulins due to
    inflammation
  • Can also be used to monitor response to treatment

21
Definitive Diagnosis
  • Cytological sampling
  • Aspiration, lavage, endoscopy, celioscopy
  • Wet mount with lactophenol cotton blue stain, new
    methylene blue
  • Culture
  • Endoscopic or swab
  • Sabourand dextrose agar or blood agar
  • Microscopic exam thick walled, septate hyphae
  • Must see spores to speciate

22
Treatment Goals
  • General
  • Prevention in captive animals is optimal
  • Clean, sanitized, stress-free environ
  • Well ventilated
  • Prophylactic use of antifungals (?)
  • Vaccine available for turkey poults for A.
    fumigatus (?)
  • Dependence on location and extent of disease
  • Aggressive therapy increases success
  • Surgical debridement of airs sac or syringeal
    lesions
  • Anti-fungal therapy

23
Antifungal Therapy
  • Goals of therapy (3)
  • Lesions restricting air flow are removed (debulk)
  • Kill or eliminate fungal organisms (antifungal
    meds)
  • Support care during recovery (fluids, Ab, force
    feed)
  • Amphotericin B
  • Intra-tracheal
  • Intra-venous
  • Nebulization
  • Oral anti-fungals
  • Flucytosine
  • Itraconazole
  • Terbinafine (Lamisil)

24
Amphotericin B
  • Only fungicidal available and is gold standard
  • Not absorbed orally
  • IV or IO (initially) for severe cases
  • Infused into air sac
  • Intratracheally
  • Nebulization

25
Azoles
  • Itraconazole
  • For less severe cases
  • Does NOT enter brain/CNS (Fluconazole does)
  • Enhanced absorption with fatty meal

26
Nebulization Therapy
  • Drug Dosage (per 15 ml)
  • Amikacin 75 mg
  • Amphotericin B 100 mg
  • Chloramphenicol 200 mg
  • Enrofloxacin 150 mg
  • Gentamicin 75 mg
  • Tylosin 150 mg

27
Nebulization
  • Drugs amphotericin B or terbinafine (Lamasil)
  • Allows penetration into air sacs
  • Must micro-size droplet 3-5 microns diameter
  • Can also administer through air sac cannula

28
Zoonotic Potential
  • Inhalation of spores
  • Dose dependent
  • Aspergillus must be sporulating
  • Cutaneous contact
  • Requires dermal integrity compromise (cuts, etc.)

29
The End
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