Recent Advances in the Ecoepidemiology, Virulence and Diagnosis of Cryptococcus neoformans and Cryptococcus gattii Species Complexes

Abstract

Emerging environmental pathogenic fungal infections, including cryptococcosis, continue to pose a significant threat to humans with compromised immunity and, to some extent, healthy ones. Cryptococcus neoformans was originally identified as the main etiological agent of human cryptococcosis, but recent studies have also identified the occurrence of opportunistic infections caused by Cryptococcus gattii. These two saprophytic facultative yeasts present a paradox as they can infect humans without requiring a host for replication or survival, a phenomenon termed readymade virulence. Many cryptococcal virulence traits appear to have dual effects that provide survival advantages in both animal hosts and the environment. Several molecular techniques have been developed to provide in-depth knowledge of these species complexes. This review will focus on the description of the Cryptococcus neoformans and Cryptococcus gattii (CnCg) species complexes and associated cryptococcal pathogenesis, ecological niches, and virulence factors employed by the pathogens to cause disease.