UBC Reports | Vol. 48 | No. 12 | Oct. 10, 2002

UBC Research Unlocking the Key to Mystery Killer Fungus

No one knows yet how it got here

By Hilary Thomson

How did a potentially lethal fungus spread by koala bears end up on Vancouver Island? That’s the mystery that UBC researcher Karen Bartlett is trying to unravel.

Bartlett, an assistant professor in the School of Occupational and Environmental Hygiene, has been traveling since March to Vancouver Island tracking down Cryptococcus neoformans var. gattii. It is a microscopic yeast typically found in eucalyptus and other tropical and sub-tropical trees. It started showing up on the Island in 1999 -- the first time ever the tropical fungus has been found in a temperate climate.

When fungal spores are inhaled, they can produce a rare infection called cryptococcosis. Affecting the lungs and nervous system, symptoms include prolonged cough and weight loss and the infection can sometimes lead to potentially fatal meningitis or swelling of the brain.

About 59 cases, including two fatalities, have been diagnosed on the Island since 1999 -- an incidence higher than anywhere else in the world. More than 35 cases in pets and wildlife have been diagnosed since 2000.

Although health risks associated with the fungus are low, physicians were educated about the disease that is complicated by patients in northern climates having no antibodies to fight the infection.

“This is a fascinating puzzle for a researcher,” says Bartlett, who is an expert on fungi and building materials. “It’s exciting to be so directly involved in finding out how this disease is spread and to be working in a natural lab out in the forest.”

The mystery started in late 1999 when Island veterinarians identified an unusual airborne infection in llamas, ferrets and other animals. Samples were sent to the B.C. Centre for Disease Control (BCCDC) in Vancouver. UBC, BCCDC and the Vancouver Island Health Authority have been working together to deal with the problem.

Reports of illness originated on the east side of the Island and Bartlett has tested trees from Parksville and Rathtrevor Beach to Victoria. She is examining samples of tree pulp taken from holes created by birds and insects and also testing bark and the air around the trees.

Eucalyptus did not show evidence of the organism but some Douglas Fir, arbutus, Garry Oak, big-leaf maple, cedar, alder and bitter cherry have tested positive for the fungus. While the yeast has actually colonized in some of the trees, nearby trees may also have tested positive simply due to wind-blown spores landing there. Bartlett has tested trees in North Vancouver and the Sunshine Coast, all of which have been negative.

She suspects birds may carry fungal spores from tree to tree. She has also found that the yeast survives well in salt water, which suggests other methods of transmission.

Future investigations will look at the range of the fungal spores; determine if the fungus is always present or seasonal; and gauge exposure risks for people working with infected trees, lumber or wood products.

“We’re going to see more unusual infectious diseases because of climate change, increased mobility and other factors,” says Bartlett, who is the recipient of a 2003 Scholar Award from the Michael Smith Foundation for Health Research. “We need to take the environment seriously, allocate resources and make changes to keep the next generation safe.”

For more information check the B.C. Centre for Disease Control Web Site at www.bccdc.org.