Aspergillosis is a disease caused by fungi of the genus Aspergillus. The most common types to affect cats are Aspergillus fumigatus and Aspergillus terreus.
The fungus is found on dead leaves, compost heaps, soil and the in the air. In cats, it typically affects the nasal cavity, respiratory system or digestive tract. In some cases, the spores can also trigger an allergic reaction in the cat.
Cats become infected when they inhale the spores of the fungus. Exposure in most cats occurs without ill effects. The disease is opportunistic, mostly affecting immunodeficient animals. Cats with feline panleukopenia are especially vulnerable to developing an infection due to their weakened immune systems.
Thankfully the disease is relatively rare in cats.
For most cats, infection is localised in the nose, however, some cases will move to the lungs. The most serious form, disseminated aspergillosis, occurs when the fungus spreads beyond the lungs and infects other organs in the body.