Alien Invasion: The Fungus That Came to Canada
Sunday, April 8, 2007
VICTORIA, B.C. -- The mystery emerged slowly, its clues maddeningly diverse.
Sally Lester, an animal pathologist at a British Columbia laboratory, slipped a slide under her microscope -- a tissue from a dog on Vancouver Island. Her lens focused on a tiny cell that looked like a boiled egg. It was late 1999. She had started seeing a lot of those.
On the eastern side of the island, several dead porpoises washed ashore early the next year. Scientist Craig Stephen, who runs a research center on the island, slit one open. He found its lungs seized by pneumonia and its other organs swollen by strange, flowerlike tumors.
At work at the family trucking firm in Victoria, on the southern tip of the island, Esther Young, a lively 45-year-old mother, was feeling lousy in the fall of 2001. She had headaches and night sweats and was tired, her family said.
The doctor told her she was pre-menopausal and it would pass.
All would become pieces of a medical mystery centered on a tropical disease apparently brought to North America by a warming climate. An alien fungus took root on Vancouver Island eight years ago and has since killed eight people and infected at least 163 others, as well as many animals.
Similar cases have been found elsewhere in British Columbia and in Washington state and Oregon. Scientists say the fungus may be thriving because of a string of unusually warm summers here. They say it is a sign of things to come.
"As climate change happens, new ecological niches will become available to organisms, and we will see this kind of thing happen again," said Karen Bartlett, a scientist at the University of British Columbia who played a central role in the search for the disease's cause.
Her investigation eventually would focus on a fungus, a member of the yeast family called Cryptococcus gattii. The microscopic fungus is normally found in the bark of eucalyptus trees in Australia and other tropical zones.
Physicians in North America are familiar with a relative, Cryptococcus neoformans. In humans, it shows up through pneumonia when immune systems already are weak, most typically in AIDS patients. In dogs and cats, it can form abscesses below the eyes. Lester, working in her pathology lab in 1999, was used to seeing tissue specimens from six to 10 pets a year with it.
But by 2000, vets on the island were sending her 10 positive samples a month. Lester knew Cryptococcus causes a disease that, like bird flu and West Nile virus, affects animals and humans. She put in a call to the British Columbia Center for Disease Control.
The call came at a busy time for Murray Fyfe. The head epidemiologist at the provincial CDC was then dealing with a bevy of other public health problems: Peanuts from China had caused salmonella. Some local spinach was tainted. And there was a surge of men coming to hospitals with diarrhea.