Cryptococcus gattii Infections on the Rise
Yeast cells of the related species C. neoformans visualized using a light India ink staining (CDC/Dr. Leanor Haley)
It’s not every day you get clued in on a story of possible mycological interest by visiting the Drudge Report (FYI, to balance things out, I also check The Huffington Post). But, there it was–Potentially deadly fungus spreading in US, Canada.
A potentially deadly strain of fungus is spreading among animals and people in the northwestern United States and the Canadian province of British Columbia, researchers reported on Thursday. The airborne fungus, called Cryptococcus gattii, usually only infects transplant and AIDS patients and people with otherwise compromised immune systems, but the new strain is genetically different, the researchers said.
(Note: Most folks don’t seem to know that species names should be italicized and therefore don’t do it. Even so, if I see that error in an excerpt, I add the italics. However, this blogging software doesn’t seem to allow italics in post titles.)
The Reuters article is based n a recent report in PLOS Pathogens, Emergence and Pathogenicity of Highly Virulent Cryptococcus gattii published by researchers in the US, UK and Australia. PLOS Pathogens is open access so I am sure they won’t mind the full abstract being reposted here:
Cryptococcus gattii causes life-threatening disease in otherwise healthy hosts and to a lesser extent in immunocompromised hosts. The highest incidence for this disease is on Vancouver Island, Canada, where an outbreak is expanding into neighboring regions including mainland British Columbia and the United States. This outbreak is caused predominantly by C. gattii molecular type VGII, specifically VGIIa/major. In addition, a novel genotype, VGIIc, has emerged in Oregon and is now a major source of illness in the region. Through molecular epidemiology and population analysis of MLST and VNTR markers, we show that the VGIIc group is clonal and hypothesize it arose recently. The VGIIa/IIc outbreak lineages are sexually fertile and studies support ongoing recombination in the global VGII population. This illustrates two hallmarks of emerging outbreaks: high clonality and the emergence of novel genotypes via recombination. In macrophage and murine infections, the novel VGIIc genotype and VGIIa/major isolates from the United States are highly virulent compared to similar non-outbreak VGIIa/major-related isolates. Combined MLST-VNTR analysis distinguishes clonal expansion of the VGIIa/major outbreak genotype from related but distinguishable less-virulent genotypes isolated from other geographic regions. Our evidence documents emerging hypervirulent genotypes in the United States that may expand further and provides insight into the possible molecular and geographic origins of the outbreak.
An interesting feature of these PLOS papers is a section called Author Summary, which seems to be a “take home message” sort of a thing that is written in less technical language:
Emerging and reemerging infectious diseases are increasing worldwide and represent a major public health concern. One class of emerging human and animal diseases is caused by fungi. In this study, we examine the expansion on an outbreak of a fungus, Cryptococcus gattii, in the Pacific Northwest of the United States. This fungus has been considered a tropical fungus, but emerged to cause an outbreak in the temperate climes of Vancouver Island in 1999 that is now causing disease in humans and animals in the United States. In this study we applied a method of sequence bar-coding to determine how the isolates causing disease are related to those on Vancouver Island and elsewhere globally. We also expand on the discovery of a new pathogenic strain recently identified only in Oregon and show that it is highly virulent in immune cell and whole animal virulence experiments. These studies extend our understanding of how diseases emerge in new climates and how they adapt to these regions to cause disease. Our findings suggest further expansion into neighboring regions is likely to occur and aim to increase disease awareness in the region.
With good open-source research and information like this directly available, there isn’t much need for me to add anything else!
More on C. gattii
Why we should care about Cryptococcus gattii
Cryptococcus gattii Research at the University of British Columbia
Deadly New Fungus Emerging in Oregon Expected to Spread
Cryptococcus gattii at University of Adelaide
A Podcast on C. gattii from the CDC
Tags: cryptococcosis, Cryptococcus gattii, fungal disease, medical mycology
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