ABSTRACT
Cryptococcosis is a human disease caused by the fungal species in the genus Cryptococcus. In Latin, the name means hidden spheres: a name selected because the fungi are both small and spherical (Figure 25.1). The species was isolated from a German patient during the 1890s. Cryptococcus are yeastlike, monomorphic fungi, which reproduce by budding. The spherical yeasts are enclosed by a thick capsule. There are over 30 species in the genus, but nearly all human cases of cryptococcosis result from just two species: C. neoformans and C. gattii. Both species are found in soils across the world. C. neoformans is associated with soil that has been enriched with bird feces, especially pigeon feces. C. neoformans cryptococcosis is rare among healthy people; the annual incidence rate is between 0.4 and 1.3 cases per 100,000, but the rate is much higher among people with HIV/AIDS. Among them, the annual incidence is 200-700 cases per 100,000 among people in the United States (CDC 2012a, 2012b).
