Fatal fungus spreads in Northwest
Global warming may have sped regional growth of a tropical fungus that has taken 8 lives.
The Washington Post
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 45-year-old mother, was feeling ill in the fall of 2001. She had headaches and night sweats and was tired, her family said. The doctor told her she was premenopausal 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 and Oregon. Health authorities in the two states say the disease is still too rare in their areas to warrant alarm, but they are watching it.
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 (UBC) who played a central role in the search for the disease's cause.
Bartlett's 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 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.
Murray Fyfe, head epidemiologist at the provincial CDC, consulted Pamela Kibsey, a microbiologist at the Vancouver Island Health Authority. Kibsey said she had noticed an increase in human cases of Cryptococcus. And there was something strange about it. It was infecting healthy people, not just the sick.
Fyfe formed a group to begin combing records of veterinarians and hospitals, tracing the first cases back to 1999. He asked Bartlett, at UBC, to join the group. They sent samples of the Cryptococcus recovered from diseased tissue for further analysis. The results showed it wasn't the familiar form.
"This was an Australian fungus," said Stephen, the scientist. More disturbing, the fungus appeared to be more deadly than in Australia. There, it infects about four people per million and is rarely fatal. On Vancouver Island, the rate was 27 per million, and it was more often killing people.
Points of origin
The scientists can only guess how, and when, the fungus arrived. It could have been brought on Australian eucalyptus trees imported by nurseries. Or it may always have been on the island, quietly clinging to life unnoticed until the warm summers spurred it to proliferate.
"With global warming, it may have finally been able to emerge to a level [at which] it is infectious," Fyfe said. Humans and animals living in the area, having had no exposure, had developed no immunities to it. Some people reacted to exposure by developing the disease.
Bartlett formed a team of students to try to find gattii in the wild. Using new detection kits ordered from Japan, they tramped through backyards on Vancouver Island, digging up soil, taking air samples, swabbing bark on trees. They went out with hourlong questionnaires to talk to survivors of the disease and to owners of infected pets.
One common site came up: Rathtrevor Beach Provincial Park, next to the Strait of Georgia. Patient Esther Young had gone to the park to kayak. Several other patients had been there.
Fyfe helped the students swab an old Douglas fir at the park. Two weeks later, Bartlett called him, excited. The swabs had come back positive, the first discovery of Cryptococcus gattii in the wild.
By the start of 2003, Bartlett's students had found the fungus in other spots. They eventually concluded it had infested a several-hundred-mile range on eastern Vancouver Island. Health officials agreed with business leaders in the adjacent city of Parksville that it was no longer fair to target the park alone, and warning signs at the Rathtrevor Beach park came down in favor of a wider information campaign.
Health authorities still are struggling to strike the right balance with the public. "It's serious, but it's still a very rare disease. Much rarer than influenza, for example," said Eleni Galanis, epidemiologist at the B.C. Center for Disease Control. "People need to be aware of it, in order to treat it. But we don't want people to stop going outside."
If doctors catch the disease early, oral doses of antifungal drugs will kill the cells. Undetected, the fungus can get into the spinal fluid, causing potentially fatal meningitis.
Young went home sick in February 2002. By that summer, she could not walk, had lost her ability to speak, had gone temporarily blind and was slowly starving because she could not keep food down. By the time doctors tested her, the fungus had reached her brain.
"My poor sister couldn't even tell anyone how she was feeling," said Deborah Chow, 51, reminiscing with her family. Finally, with Young's pain clear and the end inevitable, Chow held her sister in the hospital and whispered, "It's OK to go. Dad will be OK. Your son will be OK." She died 45 minutes later.
Tracking its progress
New cases on Vancouver Island have leveled off at about 25 a year. Bartlett's focus now is to figure out whether — and how — the fungus is moving.
Five human cases have been found on the British Columbia mainland; two people have been sickened in Washington; and Oregon has had two fatalities from a similar but not identical strain of gattii. Bartlett said it is unclear whether the fungus has been tracked elsewhere on the bottom of shoes or in wheel wells.
"One possibility for what we are seeing on the mainland is the first colonization, like we had on the island in 1999," Bartlett said. Another is that those traces will disappear.
The infected porpoises — at least 25 of them now — suggest the fungus is carried by air over the water. Stephen Raverty, a pathologist at the provincial veterinary center in British Columbia, worries that the fungus can attack other species.
Killer whales, whose numbers have dropped sharply here, are cetaceans like the stricken Dall's porpoises. Raverty and others have been tracking the killer whales in Puget Sound, using glassine slides mounted on long poles to catch droplets from the whales' exhalations, to see whether the animals have been infected.
So far, they haven't found the fungus. But animals can act as a sentinel for humans, the scientists say.
"These are the types of things we will see with climate change," Fyfe said. "As the weather in North America gets warmer, we are more likely to be affected by these public-health threats."
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