Aspergillosis is an infectious, non-contagious common fungal disease of chickens. The disease is caused by infection with species belonging to the Aspergillus
genus. Aspergillus fumigatus
is the most common species isolated from infected birds, followed by A. flavus
. There are two different forms of the disease---consisting of acute or chronic form.
- Acute form: The acute form, also referred to as Brooder pneumonia causes respiratory disease in newly hatched chicks and is associated with high morbidity and high mortality rates.
- Chronic form: The chronic form, which is the discussed on this page, usually affects older chickens. It primary causes respiratory disease, but the organism can spread to the brain and eye causing neurological signs and blindness.
Clinical signs may include coughing, loss of the ability to vocalize (caused by mucus accumulation in the trachea), and open-mouth breathing. When the eyes are infected, it may cause cloudy eyes, eye swelling, and blindness. If the central nervous system is affected, torticollis may be observed. Other generalized signs of illness include lethargy, weight loss, laying down frequently, isolation from the group, and loss of appetite.
Where the fungus is found
spp. are naturally found in small concentrations throughout the environment---in the air, soil, bedding, etc. Higher amounts of Aspergillus
spp. develop through the presence of dust and mold.
How it spreads
Aspergillosis is not a transmissible disease. Chickens are infected through environmental exposure. Aspergillus
are opportunistic invaders, and healthy birds are usually resistant to infection unless they are exposed to a massive number in the environment or are vulnerable due to age, concurrent illness, chronic inflammatory condition (such as bumblefoot or other prolonged condition) or stress. Sometimes multiple flock members become infected at the same time from exposure to the same source.