Environmental Niches forCryptococcus neoformansandCryptococcus gattii

Abstract

This chapter focuses on the environmental habitats of the dominant human-pathogenic species, Cryptococcus neoformans and Cryptococcus gattii, and their varieties and subgroups. The procedures for isolating C. gattii from any environmental sample are the same as those for C. neoformans. Several researchers have sampled specific sites temporally and spatially. Many have included a variety of telluric, arboreal, aquatic, and aerial niches. C. neoformans was recovered from 62 samples of decayed wood from the hollows of five pink shower trees, two fig trees, and one November shower tree. The majority of patients diagnosed with cryptococcal meningitis in Teresina resided in Piauḭ or the adjacent state of Maranhao. Strains of VNI can readily be isolated from pigeon feces, and they are able to grow and mate on media containing pigeon feces. As cited in the chapter, the rare environmental strains of VNII have included isolations from pigeon and arboreal habitats, but their numbers have been too low to define the ecological niche of this molecular type. C. gattii is rarely isolated from pigeon feces but is associated with various tree species in Australia, Asia, North America, and South America. These different environmental niches have led to the hypothesis that C. neoformans is ubiquitous in the environment due to dissemination by pigeons following migratory and trade routes and that C. gattii is restricted to tropical and subtropical regions because it is not associated with pigeons.