Effective Treatment for Feline Cryptococcosis: What to

What is Cryptococcus neoformans?

Cryptococcus neoformans, the causative agent of cryptococcosis, is a round yeastlike fungus with a protective outer capsule.

Why are cats more susceptible to infection?

One subspecies of Cryptococcus neoformans is a common pathogen in feline cryptococcosis, a disease often found in pigeon habitats or their droppings.

Key Points

Pigeons are the most significant vectors for Cryptococcus neoformans.

Research has shown that Cryptococcus neoformans is commonly found in pigeon nests, attics, and piles of dead leaves and branches, where pigeons frequently land.

Clinical Symptoms

Clinical cases in cats infected with Cryptococcus neoformans are generally related to infections of the upper respiratory tract, nasopharynx, skin, eyes, and central nervous system, with occasional oral ulcers.

About 40% to 50% of cases involve skin or subcutaneous tissue, presenting as papules, nodules, and potentially ulcers or inflammatory exudates, along with local lymphadenitis.

Between 50% and 80% of cases exhibit upper respiratory symptoms, such as sneezing, nasal congestion, and mucopurulent discharge from one or both nostrils, or even with blood.

Other Symptoms

Cases of central nervous system infection mainly present with symptoms like depression, abnormal behavior, seizures, circling, opisthotonos, and blindness, among other neurological signs. Cats with leukemia or immunodeficiency syndromes are more prone to central nervous system and ocular symptoms. Approximately 25% of cats develop central nervous system infections, and 20% to 25% suffer from ocular infections.

Differential Diagnosis

It is necessary to differentiate from other respiratory diseases (such as nasal tumors, nasal aspergillosis, and other fungal infections of the nose), central nervous system diseases caused by Toxoplasma gondii, and other fungal infections of the eyes and skin.

Direct Microscopy

According to symptoms, appropriate specimens (such as cerebrospinal fluid and brain lesions for encephalitis cases; respiratory secretions and lung lesions for pulmonary symptoms; and exudates and tumor tissue for skin cases) are collected for staining and microscopic examination, where the fungal bodies can be observed.

Fungal isolation and culture can reveal dropletlike, later milky, convex small colonies.

Imaging Studies

Chest Xrays may show small or large pulmonary shadows, pleural effusion, and enlargement of bronchial lymph nodes.

In cases of nasal involvement, Xrays may show increased soft tissue density and bone structure destruction in the nasal and frontal sinuses.

Blood and Biochemical Tests

There may be mild nonregenerative anemia and an increase in mature white blood cells or mild left shift.

Treatment

Early and aggressive treatment of cryptococcosis can maximize the chances of a positive outcome. Fortunately, there are many antifungal medications available, such as ketoconazole, itraconazole, or fluconazole, which are commonly used to treat feline cryptococcosis. Itraconazole (Ketek) is particularly effective compared to ketoconazole and is a newgeneration antifungal oral solution with a catspecific approval, known as Hanfuxin.