Disseminate Cryptococcosis in a Guenon (Cercopithecus ascanius)

Abstract. A 23-year-old captive-bred red-tailed guenon (Cercopithecus ascanius) with a brief history of inappetence, lethargy, and seizures was submitted for necropsy. On postmortem examination, multiple cryptococcomas were identified in brain and heart. Cryptococcus neoformans organisms were also identified microscopically in kidney, eye, and pancreas. Fungal yeast formed rare pseudohyphae. The histologic diagnosis of cryptococcosis was confirmed by a positive test for C. neoformans antigen in a serum sample. Immunohistochemical staining confirmed that macrophages were the principal inflammatory cell in brain lesions and often contained phagocytosed yeast. As disseminate cryptococcosis is often associated with immune suppression, serology and immunohistochemical staining for simian immunodeficiency virus were performed but showed no evidence of SIV infection. Key words: Brain; Cryptococcus; guenon; heart; primate. The dimorphic fungal pathogen Cryptococcus neofor-mans frequently invades the central nervous system with a propensity for the meninges in many mammalian species, including dogs, cats, horses, and primates. In contrast, systemic cryptococcosis is rare, primaril