Researchers traced the environmental source of a fungal infection that have been causing HIV/AIDS patients in Southern California for decades.

The discovery stemmed from a project conducted by a 13-year-old girl in which she collected tree samples from specimens infected with the fungus Cryptococcus gattii, Duke University reported. C. gattii can cause fatal infections in the lungs and the brain, and has been responsible for a third of all AIDS-related deaths.

The study found significant genetic evidence that Canary Island pine, Pohutukawa and American sweetgum trees can spread the dangerous infection to humans.

"Just as people who travel to South America are told to be careful about drinking the water, people who visit other areas like California, the Pacific Northwest and Oregon need to be aware that they are at risk for developing a fungal infection, especially if their immune system is compromised," said Deborah J. Springer, Ph.D., lead study author and postdoctoral fellow in the Center for Microbial Pathogenesis at Duke University School of Medicine.

Several years ago Duke's chairman of Molecular Genetics and Microbiology Joseph Heitman M.D. got a call from longtime collaborator and UCLA infectious disease specialist Scott Filler, M.D. who was looking for a project for his daughter, Elan, to work on over the summer. The researchers decided to send the young girl out to sample fungi around the Los Angeles area.

Elan took 109 swabs of over 30 tree species as well as 58 soil samples. The student then grew and isolate C. gatti fungus and sent them to Springer. The researchers compared the genetic sequences of the fungi with those HIV/AIDS patients suffering from the infection. Springer found three tree species were basically genetically indistinguishable from the human samples. Springer also observed the fungi could reproduce even when separated from the soil.

"That finding is important for long-term prevalence in the environment, because this fungal pathogen will be able to grow, reproduce, disperse spores, and serve as a source of ongoing infections," Springer said.

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