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Airborne Fungus Potentially Deadly
 
 
  MedPage Today
April 23, 2010
 
Researchers are calling for greater awareness of a new and potentially lethal fungal infection on the west coast of the U.S.
 
Although cases are still very rare, genetic variation in Cryptococcus gattii has given rise to a novel strain that is highly virulent, according to a report from the lab of Joseph Heitman, MD, PhD, of Duke University.
 
Moreover, the novel strain -- dubbed VGIIc -- appears poised to spread south along the west coast into California, the researchers said online in PLoS Pathogens.
 
The novel strain is "worrisome because it appears to be a threat to otherwise healthy people," said Edmond Byrnes III, the Duke graduate student who led the study. He and his team analyzed the genetics of C. gattii and confirmed that cases in the U.S. differ from those in British Columbia that were reported earlier.
 
Infections caused by the novel strain also appear to be more deadly than those reported earlier, with five deaths out of 21 reported cases in the Pacific Northwest -- almost 24% -- compared with about 8.7% of the 218 cases reported in British Columbia.
 
C. gattii was, until recently, considered to be a tropical fungus. But in 1999 it emerged on Vancouver Island, where cases were largely confined until 2003.
 
Between 2003 and 2006, the outbreak expanded into mainland British Columbia and then further south into Washington and Oregon between 2005 and 2009. (See ICAAC-IDSA: Fungal Pathogen Invading Northwest)
 
"Based on this historical trajectory of expansion," the researchers said, "the outbreak may continue to expand into the neighboring region of Northern California, and possibly further."
 
In a series of experiments, the researchers established that the novel strain -- so far found only in Oregon -- emerged recently, but shares virulence characteristics with the VGIIa/major strain that has been causing disease further north.
 
The symptoms of C. gattii infection can appear two to several months after exposure, and include a cough that lasts for weeks, sharp chest pain, shortness of breath, headache, fever, nighttime sweats, and weight loss, the researchers said in a statement.
 
The fungus also infects animals; the VGIIc strain has been isolated from alpacas, cats, and dogs, while other strains have been found in elk and porpoises.
 
Because alpacas, cats, and dogs don't migrate, Byrnes said in a statement, it's likely they acquired the VGIIc strain locally in Oregon, although attempts to isolate the fungus from the environment have so far been unsuccessful.
 
"The continued expansion of C. gattii in the U.S. is ongoing, and the diversity of hosts increasing," the researchers wrote in the journal. "Physicians and veterinarians should be well informed of symptoms to facilitate early diagnoses and successful isolate collection and tracking."
 
Although the novel strain has not yet been seen in California, the expansion of the outbreak into the state is "plausible," the researchers wrote, since several studies have found other strains of the fungus in the environment, in animals, and in humans.
 
 
 
 
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