If it weren’t so deadly, the B.C. invasion might have been the subject of a bad horror flick “The Fungus Amongst Us.”
Causes of the fatal infection that hit Vancouver Island in 2001 were as mysterious as alien microbes from outer space. The ominous harbingers of human fatalities were the bloated dead porpoises that washed ashore with yeast-packed lungs and organs twice the normal weight. Some cats and dogs suffered from a mysterious lung malady. In some cats, a yeast infection had eaten holes through their skulls before they died.
Then doctors and clinics started to see patients with an unknown respiratory malady that left them coughing constantly, their energy sapped, sleep stolen. By 2012, 337 British Columbians had been infected with a mortality rate of nearly 30 per cent reports Jennifer in her article for Scientific American, Fungi on the March.
That mortality rate is high enough to categorize the infection as an outbreak. While most of the fatalities were among those with weakened immune systems and other underlying complications, 20 per cent were healthy people who spent a lot time outdoors.
At first the B.C. Centre for Disease Control had no clue. Then reports started coming in from veterinarians concerning fungal infections in cats and dogs. But unlike the usual fungus, this one was a totally foreign variety found on Australian eucalyptus trees.
The hunt was on for the source. Tests on the few eucalyptus trees that grew on Vancouver Island came up negative. Activities such as gardening, handling mulch, and cutting down trees were not a contributing factor. Nor were visits to Australia. To add to the mystery, the infections were not clustered about any epicentre but spread up and down the eastern side of the island.
The break came after infected patients, not from the island, indicated that they had visited Rathtrevor Beach Provincial Park. To everyone’s surprise, the deadly foreign fungus was found in a native tree species –the Douglas fir. Bewilderingly, the fungus was found all over the island in the soil and trees from Victoria to all but remote parts.
Yes, virtually all on Vancouver Island had been exposed for decades. The length of time since the fungi’s first arrival can be determined by its genetic diversity: the greater the diversity, the longer it’s been around.
However, it has been around long enough to evolve into more deadly sub-varieties. Three distinct strains have been identified and the outbreak has spread to the B.C. mainland, Washington state, and Oregon.
To add bafflement to bewilderment, the strain of fungus infecting those in Oregon is not the strain infecting British Columbians. How could it be that two different infectious strains of a foreign fungus originally dormant, now found on domestic trees, could evolve in separate places?
There is no hard evidence but there are the usual suspects: climate change and human activity. Plant fungi have been traveling north at the brisk rate of seven and one-half kilometres a year since 1960. Climates that were previously marginal now allow for fungus to thrive.
Humans have helped. An expressway has been extended on Vancouver Island; trees cut down; soil disturbed by new suburbs.
Fungi are below the radar of health professionals compared to viruses and bacteria; despite having a more complex genome which could give it an advantage when it comes to response to temperature stress factors.