‘Highly Virulent’ Strain of Killer Fungus Found in Ore.

(April 22) — A potentially life-threatening new type of fungus has been discovered in Oregon, and experts are warning that it could soon spread into neighboring regions.

The pathogen is a strain of Cryptococcus gattii — C. gattii for short — and appears to have a death rate of around 25 percent among those infected, although researchers have only evaluated 18 human and 21 animal cases, all of which occurred between 2005 and 2009.

Their study is published in this week’s issue of PLoS Pathogens.  Edmond Byrnes, Joseph Heitman / mgm.duke.eduCryptococcus gattii spreads by airborne spores. Symptoms include chest pain, a persistent cough and breathing problems.Experts are particularly concerned because the fungus, which infects via airborne spores, seems to affect otherwise healthy individuals. Pathogens like C. gattii are usually only a problem for those with a compromised immune system, such as transplant recipients and HIV/AIDS sufferers.

“Overall it’s a pretty low threat, and it’s still uncommon in the area, but as the range of the organism expands and the number of cases increases accordingly, it’s becoming more of a concern,” Edmond Byrnes III, a doctoral student in molecular genetics and microbiology at Duke, told CNN.

When the fungal spores are inhaled, they lodge in the lungs and respiratory tract. Symptoms, which can take months to appear, include a persistent cough, chest pain and difficulty breathing.

C. gattii is one species of Cryptococcus, a fungus usually associated with bird droppings. In humans, Cryptococcus neoformans infection is relatively common among HIV patients, who are therefore advised to avoid areas with lots of birds, according to the Centers for Disease Control and Prevention.

Until 1999, C. gattii was isolated to tropical regions. Then cases began popping up in the Pacific Northwest, including an outbreak on Vancouver Island that killed 9 percent of the 200 people believed to have been infected.

Experts suspect the original strain was imported via foreign plants and that this latest C. gattii mutation, described as “highly virulent,” is a new occurrence.

It’s unclear what factors might predispose a seemingly healthy person to infection. Young and old, male and female, smoker and nonsmoker — all seem to be at equal risk. And while it’s well known that C. gattii can be found in trees, it’s unknown whether an individual needs to breathe air near a tree to get sick.

“Our best guess is that it’s mostly associated with trees and soil, so certain disturbances might allow the organism to become airborne and more or less float in the area,” Byrnes said.

Person-to-person transmission doesn’t seem to be a problem. That’s good news, although experts can’t offer much advice in terms of prevention, and the study notes that treatment, which relies on anti-fungal medication, can take years.

Moreover, “physicians could potentially miss the diagnosis,” Karen Bartlett, an environmental hygienist with the University of British Columbia, told Science News, while adding that the infection is still quite rare.

A working group of doctors and public health officials has already been formed in the Pacific Northwest, and the study’s authors are calling for ongoing research and monitoring to stave off the spread of the fungus.  

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