Scientists estimate that roughly 1.5 million different species of fungi exist on the planet--some good, some bad, all ugly—yet only about 5 percent have been formally classified. For example, in the "bad" column, there's Aspergillus flavus, a fungus that has the potential to contaminate stored grain, where it produces a carcinogenic toxin. More infamous are toadstools, a general term for the 100-plus species of wild mushrooms that are poisonous enough to sicken or possibly kill the person who mistakes one for a safe woodland snack. And then there's the deadly Vancouver Island strain of C. gattii, which has turned out to be even more mobile and adaptable than mycologists first thought. In the years since it originally appeared on the island, the fungus has spread to mainland British Columbia and then sent tendrils down to Washington and Oregon. Last spring, Duke University researchers announced that it could spread into Northern California.
Spooked? Nearly as creepy is the reality that without certain fungi, the human race might have died out a long time ago. "If we didn't have composting of the leaves in autumn, we wouldn't have evolved because there wouldn't have been any room," says Bartlett. "And without fungi, there would be no penicillin or any other antibioticNor would cholesterol-clearing statins have been developed, because they were originally derived from such fungi as Aspergillus terreus and Penicillium citrinum. One study from the University of Dundee, in Scotland, even suggests that minerals produced by a fungus might help clean up toxic war zones by absorbing and "locking in" the depleted uranium used in ordnance such as armor-piercing rounds. "The hope is that this could help prevent plants and animals from absorbing the radioactive material," says Geoffrey Gadd, Ph.D., a professor of microbiology and the lead author of the 2008 study.
"It might also stop uranium from leaching out of the soil into the groundwater."
Such is our love-hate relationship with fungi: They can be friend or foe, lifesaving or, as in the case of Mike Merriman, life taking.
At first, doctors guessed that Merriman had pneumonia, or perhaps the flu. They did blood tests. He was put on antibiotics. They took a chest x-ray, an ultrasound, and a CT scan. After numerous doctor visits, Merriman's mother, Barb, started searching online and came across articles about C. gattii: The symptoms were surprisingly similar to what her son was experiencing. But doctors initially dismissed her theory that C. gattii could be the cause. It wasn't until Merriman was admitted to an emergency room that a doctor finally tested him for the organism. The mystery was solved—too late. The fungal spores had colonized his lungs. His central nervous system had also become infected, triggering a form of meningitis. He died that evening.
When Bartlett received word of Merriman's death, she wasn't surprised. She'd been tracking C. gattii since 2001, after the British Columbia Centre for Disease Control had contacted her about several land and marine mammals killed by the fungus, including cats, dogs, porpoises, ferrets, elk, alpacas, and sheep. One of the first human victims, Esther Young, a healthy 45-year-old woman from Victoria, British Columbia, who visited Rathtrevor Park, succumbed to C. gattii in 2002.
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