A newly discovered strain of an airborne fungus has caused several deaths in Oregon and seems poised to move into California and other adjacent areas, according to scientists at Duke University Medical Center.
“This novel fungus is worrisome because it appears to be a threat to otherwise healthy people,” said Edmond Byrnes III, a graduate student in the Duke Department of Molecular Genetics and Microbiology. “Typically, we see this fungal disease associated with transplant recipients and HIV-infected patients, but that is not what we are seeing.”
Byrnes and other Duke co-authors work in the laboratory of senior author Joseph Heitman, MD, PhD, chair of the Department of Molecular Genetics and Microbiology.
Their new work on the emergence and virulence of the new genotypes of Cryptococcus gattii fungi in the United States was published online in PLoS Pathogens on April 22.
The mortality rate for recent C. gattii cases in the Pacific Northwest is running at approximately 25 percent out of 21 cases analyzed in the United States, compared to a mortality rate of 8.7 percent out of 218 cases in British Columbia, Canada, the researchers said. Most have a more complicated clinical course than people infected with the more common Cryptococcus neoformans.
Because the strain is so virulent when it infects some humans and animals, the researchers are calling for greater awareness and vigilance. Testing involves culturing the fungus and then sequencing its DNA to learn whether it is the virulent or more benign strain, which could affect treatment plans.
Some strains of C. gattii are not more virulent than C. neoformans, for example, but doctors need to know what type they are dealing with, Byrnes said. Using molecular techniques, the geneticists uncovered clues that showed the Oregon-only fungal type most likely arose recently, in addition to an outbreak of C. gattii that began in Canada in 1999 that has now spread into Washington and Oregon.
