Aspergillosis

• Worldwide

• Common laboratory contaminants

Aspergillus cleistothecia Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

• Widely found in nature
  • Colonise a wide range of substrates under different environmental conditions
  • Abundant in hay, straw and grain which have heated during storage

• Pathogenic species include Aspergillus fumigatus, A. flavus, A. nidulans, A.niger and A. terreus

• May cause primary or secondary disease
  • Infection may be acute, chronic or benign

• Avians:
  • Diffuse infection of the air sacs
  • Diffuse pneumonic form
  • Nodular form involving the lungs
  • Spores are inhaled
  • Yellow nodules in the lungs and air sacs
  • The acute form usually affects young birds and is rapidly fatal (within 24-48 hours)
    • Signs include diarrhoea, listlessness, pyrexia, loss of appetite and loss of condition
    • Sometimes convulsions may occur
    • Resembles Pullorum disease
  • The chronic form usually occurs in adult birds and is sporadic, presenting with milder clinical signs

Aspergillus in a swan Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

• Cattle:
  • Infection can cause abortion and ocular infections
  • Infections involve the uterus, fetal membranes and fetal skin
  • Lesions are usually up to 2mm in diameter and contain asteroid bodies with a germinated spore in the centre
    • Acute infection causes miliary lesions
    • Chronic infections causes granulomatous and calcified lesions

• Horses:
  • Guttural pouch mycosis common
  • Infection can cause abortion
  • May cause COPD

• Dogs, cats and sheep:
  • Infections occur, but infrequently
  • lungs and nasal cavity most usually affected
  • Disseminated form with granulomas and infarcts can occur in dogs
  • Pulmonary and intersitital forms can occur in cats

Aspergillus in vivo Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

• Humans:
  • Primary and secondary infections
  • lungs, skin, nasal sinuses, external ear, bronchi, bones and meninges all affected
  • Infection occurs most frequently in immunocompromised patients

• Grows on Sabauraud's Dextrose and Blood agar
  • White colonies intitially which turn green, then dark green, flat and velvety
  • Colony colour varies with species

• Also grows on Czapek-Dox agar and 2% malt extract agar supplemented with antibacterial antibiotics

• Microscopically:
  • Conidiophores with large terminal vesicles (only visible in the lungs and air sacs where there is access to oxygen)
    • Vesicle shape varies depending on the species
  • Is a common contaminant so repeated tests should be done for a definitive diagnosis

• Serology:
  • Gel immunodiffusion for canine nasal asper

• Treatment:
  • Surgery
  • Antifungal drugs
    • Ketoconazole, Nystatin, Amphotericin B, 5-fluorocytosine, Thiabendazole

• Pathology:
  • Aspergillus fumigatus causes rhinitis, respiratory tract inflammation and sinusitis
  • Sometimes appears on lesions of ethmoidal haematoma

Aspergillus sporing heads Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Aspergillus mycelium stained with blue/black Quink Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Mycotic Abortion caused by Aspergillus Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Mycotic Abortion caused by Aspergillus Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Mycotic Abortion caused by Aspergillus Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Nasal Aspergillus Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Canine nasal aspergillus radiograph Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath