Asperigillosis is an infection or allergic reaction caused by the Aspergillus fungus, which commonly grows on rotting vegetation. Some people with asthma are allergic to Aspergillus and develop allergic bronchopulmonary aspergillosis (ABPA). The symptoms include wheezing and blood-stained sputum.

Although Aspergillus fungi are commonly found in the environment farmers are most at risk when working with composting or decaying vegetation such as rain damaged hay, silage or mouldy grain.

Heavy rainfall and damp conditions increase the incidence of moulds in hay and composting vegetation.  Mouldy hay can contain Aspergillus mould spores which are tiny at 2-3 microns and can go deep into your lungs when inhaled, causing respiratory illness.

If hay is baled at high moisture content levels it can increase the likelihood of hay becoming mouldy. When purchasing hay you should also check for the presence of mould. Hay which is darker in colour or has a musty smell is indicative of mould being present.

Aspergillosis in animals

Horses, dogs, cows and birds are also susceptible to Aspergillosis if exposed to mould spores as a result of being fed mouldy hay or grain, especially in poorly ventilated, confined areas Mouldy hay can contain toxins that are harmful to stock especially pregnant milking cows which can lead to abortion.


As a minimum precaution when handling mouldy hay or composting vegetation, reduce your exposure to spores and dust by wearing a P2 mask that complies with Australian Standards. Fitting the mask correctly is essential, as the presence of facial hair such as beards or even being unshaven can reduce the effectiveness of the mask. Facial hair can be 15 microns and as Aspergillus spores are 2-3 micron effective fitting masks is vital.

Find out more on Better Health Channel

Fast facts:

  • Is an infection or allergic reaction caused by the Aspergillus fungus that can cause respiratory illness
  • Aspregillosis can also affect animals such as horses, cows, birds and dogs
  • When working with mouldy hay or grain always wear a well fitted P2 dust mask to prevent spores from being inhaled
  • Avoid feeding cows or horses mouldy hay or grain

References used for this topic

More information:

Better Health Channel

The Fungal Research Trust
The Aspergillosis website

Clinical care:

Australasian Society of Infectious Diseases
Guidelines for the use of antifungal agents in the treatment of invasive Candida and mould infections [PDF 70kb]

International Journal of COPD
Management of invasive aspergillosis in patients with COPD: rational use of voriconazole [PDF 169kb]

Research and Reviews:

Journal of Fungi
Allergic Bronchopulmonary Aspergillosis (2016)