The symptoms of a systemic fungal infection in cats vary according to the type of fungus and the areas of the body that are affected. In general, cats with systemic fungal infections are usually very unwell and often suffer from weight loss, lethargy, fever, and poor appetites. However, these signs are not specific for fungal infections.
As many fungal infections first enter the body inhaled through the nose, symptoms affecting the respiratory tract (such as nasal discharge, difficulties breathing, and swellings on the bridge of the nose) are common. From here, some fungi spread to the brain and central nervous system causing neurological signs (these can include blindness, seizures, depression, and circling).
However, fungal infections can spread to almost any area of the body, and so the range of possible symptoms is very wide.