Floating Fungus: Trouble in the Air?

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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Bartlett traveled to Rathtrevor with her research team, made up primarily of her students, and began collecting soil samples and swabbing trees. "By the end of that summer, we had mapped C. gattii colonies all the way down to Victoria," she recalls. To date, more than 250 C. gattii infections have been reported in British Columbia. The mortality rate: about 9 percent. By contrast, the 2009 H1N1 "swine flu" virus had a mortality rate under 1 percent. Bartlett suspects that even more unreported cases may have been out there, perhaps from people who just assumed they'd been sick with something else. "There is no question that mild or asymptomatic cases are present but not counted," she says. "A few of the cases were diagnosed simply because the person was having a chest x-ray done, and a cryptococcus nodule was discovered."

Since 2004, 70 people have been infected with C. gattii in the United States, according to Julie Harris, Ph.D., M.P.H., a staff epidemiologist with the U.S. Centers for Disease Control and Prevention. Sixteen have died. "We are still seeing increasing numbers of cases in the United States each year."

Fortunately, unlike many bacterial and viral infections, a bout with C. gattii doesn't mean its victim is contagious. Another consolation is that only a tiny fraction of those exposed to C. gattii become sick, and when they do, the infection is treatable with antifungal medications. But this assumes that the physician actually knows what to treat. Until recently, doctors in the Pacific Northwest were routinely misdiagnosing the illness as flu, pneumonia, or even lung cancer. "They would see these lung nodules and make the diagnosis," Bartlett says. "In one of the first cases, a doctor told a patient, 'I've got good news and bad news for you: The good news is you don't have cancer; the bad news is you have AIDS.'"

Because the topic of fungi garners scant attention beyond a relatively small circle of mycologists, awareness has been slow in coming. "It's appalling how little time is spent in medical school training students to diagnose fungal infections," says Kadosh.

"People are dying out there from fungal infections because doctors don't know how to diagnose them."

Bartlett agrees. "One of the big challenges for us was to convince physicians to say, 'Hey, there's a new organism on the block that's going to be affecting people with apparently healthy immune systems,'" she says. "'It's going to look like lung cancer, but it isn't.' "

For all the wondrous—and destructive—things fungi can do, they seem to lack the crucial ability to attract researchers. "Even though fungi are the most fascinating critters in the world, there aren't that many scientists who think so," says Mueller. "The number of people studying the great diversity of species, and the great diversity of questions, is just downright small."

One reason is the competition. Yes, fungi are higher on the evolutionary ladder than, say, bacteria and viruses. And as C. gattii has shown, they are just as effective at causing disease and death. But bacteria and viruses still hog the scientific spotlight—and research dollars.

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Fungal infections in particular are "kind of a neglected area," says Kadosh. "About 30 different classes of antibiotics are available, but only five major classes of antifungals." As is often the case, it sometimes takes an outbreak like the C. gattii episode--the more mysterious and deadly the better—to catch our attention. Indeed, soon after the outbreak at Rathtrevor Park, the British Columbia Centre for Disease Control sent letters to all physicians in British Columbia to alert them to the presence of the fungus on Vancouver Island. Unfortunately, as Bartlett points out, that didn't help Merriman. Nor does it help someone like me, a visitor to the island who then goes home to Chicago and might develop a cough 6 months later.

All of which points out a dilemma: There's this scary . . . thing . . . out there randomly spitting spores, a thing that has the power to kill you if your doctor doesn't know to look for it as a cause of mysterious flulike symptoms. You probably won't become infected with it, but then again, no one can say for sure you won't. But hey, don't lose sleep over it, and by all means keep tromping through those Pacific Northwest fungi forests and reserving campsites.

One thing that is clear is that C. gattii has spread from Vancouver Island to mainland British Columbia to the United States. The mystery is how. And why now? C. gattii had previously been found only in Australia, among eucalyptus trees. Was the fungus somehow brought here? If it was, why has it taken hold only in the Northwest?

There are no definite answers, but Bartlett has theories. She doubts, for instance, that the fungus was imported, because the C. gattii strain found in the Pacific Northwest differs from strains found in other parts of the world. Instead, she believes, the fungus had probably been dormant on Vancouver Island all along, perhaps for thousands of years, and had been kept in check by other organisms.

So what happened? "In this case, we think that what's been changing is the climate," she says. "Over the past 40 years, the average temperature in British Columbia has increased. Average snow cover in winter has decreased. Drought frequency has increased. That tiny climate shift was probably enough to suddenly give C. gattii an advantage over other microorganisms that it previously had been in dynamic balance with." Translation: Thanks to global warming, C. gattii suddenly became the bully on the block. Combine that with the rain-soaked environment of the Pacific Northwest, Bartlett says, and you have the ideal makings for a fungi fairyland.

As it turns out, C. gattii's predilection for the soggy and boggy is good news when it comes to its potential for showing up in other parts of the United States, says Harris. "Fungi are very particular about climatic conditions, and it's unlikely that we'll see C. gattii spreading to areas with drastically different climates than those found in the Pacific Northwest and California." Certain parts of the United States are similar enough to the current outbreak zone that the fungi could potentially flourish, but it's hard to predict where and when that could occur. "More likely, we will see cases among travelers to the Pacific Northwest and California," Harris says.

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The U.S. Centers for Disease Control and Prevention has been trying to spread the word, sending out bulletins to doctors and clinicians and presenting at conferences to heighten awareness of the fungal outbreak. Still, "with a new infection, it's always a challenge," Harris acknowledges.

"Physicians around the country should be aware of this problem, and should ask their patients about their travel history during the year before they became ill."

In Rathtrevor Park, all is quiet among the trails that meander inland from where the whitecapped waters slap against the shore. The campsites here—small, worn clearings a few paces apart from one another under the fir-and-maple canopy—are unoccupied, except for one couple relaxing in foldout chairs next to an old Winnebago.

Nearby, in a grass meadow, an old man walks with his dog. A mother and son venture to the water, admire the bleached-white bones of an uprooted tree trunk, snap a photo. If concerns linger about whether it's safe to visit here, there's no sign of it today.

Perhaps sensing my uneasiness, Karen Bartlett and even Barb Merriman have encouraged me--and urge anyone else so inclined--to come back and visit.

"We still enjoy the trails and parks on Vancouver Island," Barb Merriman says, "and will continue to do so. Cryptococcus gattii is low risk—I do not want people to worry about it. Just be informed."

Her words reassure me a little as I take one last turn around the grounds, stare once more up at the magnificent trees. Still, later on as the ferry pulls away from Nanaimo, I breathe a little easier.

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