22 August 2014

Fungus deadly to Aids patients grows on trees

A 13-year-old girl found the environmental source of fungal infections that have been sickening HIV/Aids patients in Southern California for many years.


Researchers have pinpointed the environmental source of fungal infections that have been sickening HIV/Aids patients in Southern California for decades. It literally grows on trees.

Life-threatening infections

The discovery is based on the science project of a 13-year-old girl, who spent the summer gathering soil and tree samples from areas around Los Angeles hardest hit by infections of the fungus named Cryptococcus gattii (CRIP-to-cock-us GAT-ee-eye).

Cryptococcus, which encompasses a number of species including C. gattii, causes life-threatening infections of the lungs and brain and is responsible for one third of all Aids-related deaths.

Read: HIV and fungal infections

The study, which appears in PLOS Pathogens, found strong genetic evidence that three tree species – Canary Island pine, Pohutukawa and American sweetgum – can serve as environmental hosts and sources of these 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 Centre for Microbial Pathogenesis at Duke University School of Medicine.

In search of fungi

A few years ago, Duke's chairman of Molecular Genetics and Microbiology, Joseph Heitman M.D., was contacted by longtime collaborator and UCLA infectious disease specialist Scott Filler, M.D., whose daughter Elan was looking for a project to work on during her summer break. They decided it would be fun to send her out in search of fungi living in the greater Los Angeles area.

Read: No fun in fungus

The student sampled 109 swabs of more than 30 tree species and 58 soil samples, grew and isolated the Cryptococcus fungus, and then sent those specimens to Springer at Duke. Springer DNA-sequenced the samples from California and compared the sequences to those obtained from HIV/Aids patients with C. gattii infections.

She was surprised to find that specimens from three of the tree species were genetically almost indistinguishable from the patient specimens.

The researchers also found that the C. gattii isolated from the environment were fertile, reproducing either by 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.

Read more:
Fungus-tainted corn spreading HIV?
Nail fungus drug may help against HIV
Candidiasis and HIV

Image: Foot fungus disease from Shutterstock

See breaking news and the hottest health tips before anybody else by joining South Africa’s biggest and best health community, like health24 on Facebook now!



Read Health24’s Comments Policy

Comment on this story
1 comment
Comments have been closed for this article.

Ask the Expert

HIV/Aids expert

Dr Sindisiwe van Zyl qualified at the University of Pretoria before working for an HIV/AIDS NPO in Soweto for many years. She was named one of the Mail & Guardian's Top 200 Young South Africans in 2012.

Still have a question?

Get free advice from our panel of experts

The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

* You must accept our condition

Forum Rules