Byrnes EJ, III, Li W, Lewit Y et al: Emergence and pathogenicity of highly virulent Cryptococcus gattii genotypes in the northwest United States, PLoS Pathog 6:e1000850, 2010.
The fungus Cryptococcus gatti has the potential to cause life-threatening illness in humans and animals. It is the most common systemic fungus infecting cats. In the last decade, C gatti has emerged as an important pathogen in northwestern North America, including Canada and the US. Normally it is found associated with Eucalyptus trees in tropical and subtropical regions. The emergence of this pathogen in temperate climates may indicate an expansion of its ecological niche. Genetic analysis of this pathogen, as for many others, provides important epidemiologic information. These researchers genetically characterized a number of isolates from the Pacific NW outbreak. The strains from these outbreaks, known as VGIIa and VGIIc, were found to be genetically related and are more virulent than typical strains of C. gatti. In addition, they found that the outbreak is expanding, and the diversity of hosts infected is increasing, affecting a range of mammals in urban and rural areas. The rising incidence of cryptococcosis in humans and animals in this region indicates the need for increased awareness. While still rare, it is unclear why certain humans and animals become infected (i.e. what are the risk factors?). Expansion of the outbreak into California is plausible. The precise origin of these more virulent strains remains unclear. [VT]Related articles:MacDougall L, Kidd S, Galanis E et al: Spread of Cryptococcus gattii in British Columbia, Canada and detection in the Pacific Northwest, USA, Emerg Infect Dis 13:42, 2007.