Cryptococcosis is the most common of the systemic fungal diseases in cats worldwide. Cats are more commonly affected than dogs. The infection is thought to be acquired from the environment, and cases of disease transmission from one infected animal to another have not been reported. It is not considered zoonotic. Occasional outbreaks of infection in people and animals may be caused by a common environmental source. The fungus is found in soil and bird droppings, especially in pigeon droppings. Transmission is by inhalation of spores usually within the nasal passages or contamination of wounds. Cases in strict indoor cats have also been documented. This could reflect air, or indoor soil, plant material, transfer outdoors on clothes and shoes etc.
Cryptococcosis is most commonly caused by two yeast species Cryptococcus neoformans and Cryptococcus gattii.

Clinical Signs
Upper respiratory tract signs are most common and include sneezing and nasal discharge. Crusty lesions on the head, enlarged lymph nosed and a firm swelling over the bridge of the nose may be present. The fungus may penetrate the brain, eyes lungs and other tissues resulting in eye abnormalities, neurological signs, skin ulcerations, vomiting and diarrhea. Patients may also present with a fever, inappetance and lethargy.

There are several diagnostic tests to diagnose the disease. Aspirates of the mucous material from the nasal passages or from the swelling over the nose may be submitted for cytology or cultured. Biopsy of the affected tissue can also give definite diagnosis. Antigen titers can be performed to reveal the extent of the infection. Radiographs may show soft tissue material filling the nasal passage. Cat scan and MRI are best for identifying brain and nasal lesions. Routine CBC and biochemistry are usually normal.

Treatment is costly and requires substantial owner compliance and commitment. Anticipated duration of treatment is 6 months to 1 year. Antigen titers and liver enzymes are monitored monthly during treatment. Treatment must continue until titers are negative for at least 1 month on 2 different samples. Antigen titers are then performed 1-2 months after treatment to monitor recurrence since reinfection can occur. Ideally patients should have antigen titers performed every 6 months long term to ensure permanent elimination of infection.
There are 5 antifungal drugs (Fluconazole, Itraconazole, Ketoconazole, Flucocytosine and Amphotericin B) available for treatment. Each drug has a specific role in therapy which varies depending on the patient being treated.
Surgical excision may be performed to remove masses within nasal passages or areas of extensive involvement. Surgery may be needed for successful treatment when large areas are affected.

Case of the month
Patient is a 10 year old male castrated DSH that presented with a 2 week history sneezing and a soft swelling just above his left eye that was not responsive to antibiotics. Blood work performed was unremarkable. Radiographs of the head revealed soft tissue swelling adjacent the frontal sinus and left eye. Cytology was performed on a small amount of purulent material obtained from the swelling above the eye and revealed Cryptocococcis organism. Antigen titers were performed to evaluate the extent of the disease. The patient is currently being treated daily with Fluconazole with monthly rechecks to evaluate bloodwork and antigen titers. Patient is responding well to treatment.