Fungus Deadly to AIDS Patients Found to Grow on Trees

A new study highlights the environmental source of fungal infection that has been worsening the condition of HIV/AIDS patients residing in Southern California for decades.

This finding by Duke University researchers is based on the science project done on a 13-year-old girl who was engaged in collecting soil and tree samples in region around Los Angeles during the summer. This region was hit by infections caused by fungus named Cryptococcus gattii.

Cryptococcus consists of a large number of species including C.gattii and triggers life-threatening infection of the lungs and brain. This is known to cause nearly one-third of the AIDS-related deaths. This is the first study to present strong evidence that indicates tree species like Canary Island pine, Pohutukawa and American sweetgum, can be a potential environmental host and source of human infections.

"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.

UCLA infectious disease specialist Scott Filler, M.D., daughter Elan conducted an investigation looking for fungi living in greater Los Angeles area. They sampled a total of 109 swabs from more than 30 tree species and 58 soil samples that grew and isolated the Crytpococcus fungus.

The specimens collected were later sent to Springer at Duke, who DNA-sequenced the samples collected from California and then compared them to those that were obtained from HIV/AIDS patients diagnosed with C.gattii infections.

They were surprised to see that C.gatti isolated from the environment were fertile, that reproduced either through sexual or asexual reproduction.

"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.

The finding was documented in PLOS Pathogens.