Molecular tests shows deadly fungus from B.C. moving into U.S. Northwest

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Molecular tests shows deadly fungus from B.C. moving into U.S.

Northwest

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The Canadian Press - TORONTO

http://www.google.com/hostednews/canadianpress/article/ALeqM5i6X9xsueA

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TORONTO — The outbreak of the fungus Cryptococcus gattii that has

afflicted Vancouver Island and the B.C. Lower Mainland has definitely

moved into Washington State and Oregon, a new study reveals.

Molecular analysis done by American researchers confirms that most of

the human and animal cases of C. gattii that have been recorded in

the past few years in the Pacific Northwest were caused by the two

genotypes seen in the B.C. outbreak.

The senior author of the study, to be published in the April issue of

the Journal of Infectious Diseases, said it seems likely those

outbreak genotypes will continue to spread over a wider geographic

turf - a worrisome scenario.

" It's sobering to think about this expanding its range and becoming a

real public health threat, " said Dr. ph Heitman, a microbiologist

at the department of molecular genetics and microbiology at Duke

University in Durham, N.C.

The fungus, which is found in multiple spots on the east coast of

Vancouver Island and in parts of the B.C. Lower Mainland, currently

infects an average of 25 to 28 people a year in British Columbia.

Since 1999, when it is believed the outbreak began, there have been

239 cases and 19 deaths, said Dr. Eleni Galanis of the British

Columbia Centre for Disease Control.

People who are made sick by the fungus can have lung symptoms -

coughing, shortness of breath - that mimic pneumonia or can even be

confused with lung cancer. In a small portion of cases, the fungus

causes meningitis, an inflammation of the tissues covering the brain.

The first human case in the U.S. thought to be associated with this

outbreak was reported in 2006, in a man who lives on an island in

Puget Sound, south of Vancouver Island. And other human and animal

cases have been seen since.

But the Duke team, with colleagues from s Hopkins University in

Baltimore, Md., and Oregon State University in Corvallis, looked at

the genetic barcodes of isolates from the various cases to determine

whether the U.S. ones were representative of spread of the fungus

from B.C. or were the work of another genotype of the fungus

altogether.

They found that while most of the U.S. cases seen to date were caused

by the two genotypes found in British Columbia - they are known as

VGIIa and VGIIb - there were actually a handful of cases in Oregon

caused by a new genotype called VGIIc. Three of those cases were in

people; there were two animal cases, a cat and an alpaca.

And one human case, in southern Washington State, was caused by the

genotype VGIII, which has been found previously in Australia.

Proof the fungus has spread comes as no surprise to scientists who

have been working on this unusual outbreak, which marks the first

time Cryptococcus gattii has been seen to become entrenched in a

temperate location.

Computer modelling suggested this might happen, said Bartlett,

an expert in airborne biohazards with the University of British

Columbia's school of environmental health.

" This fits the pattern, " said Bartlett, who has been studying the

pathogen for years.

No one knows for sure how or why a fungus more commonly found in the

Australian outback and rural South America seems to have suddenly

gained a foothold on Vancouver Island.

But one theory is that climate change has created a more hospitable

environment for the fungus, allowing it to reproduce and flourish in

new areas.

Bartlett said the work from Heitman's lab bolsters that theory.

She suggests the fungus may have had repeated introductions to the

region over time, but only managed to seed itself and become present

in high enough concentrations to cause disease once conditions in the

region became more favourable to it.

" The fact that we've not seen - and we've looked really hard for it -

the VGIIc on Vancouver Island or the VGIII on Vancouver Island to me

is probably telling us that there's been multiple introductions of

gattii over the eons of time, " she said.

It's not clear how far the outbreak genotypes might spread, though

Galanis and Bartlett think places with long, cold winters probably

wouldn't be at much risk.

" I think it's really hard to say at this point, " Heitman said. " I

think if we look at how it's expanded so far, it's been to the east

and south. And definitely the climate is much colder and the tree

species are different as you get further into the country. "

" My own bet would be that it would go down the coast. But they're

certainly setting up to do surveys in Idaho and Montana and Nevada

and California. "