Strange Fungi Now Stalk Healthy People
Fungi have long plagued plants—famously felling the towering elm and chestnut trees of the eastern U.S. and beyond. More recently, fungal epidemics have become alarmingly common among animals. From ponds in South America where frogs' fungus-clogged skin stops their heart to caves in the eastern U.S. where moldy, shivering bats drop pitifully from the ceiling, pathogenic fungi are running amok. Historically the fungi that infect humans have been known more for inspiring laughably bad commercials about trifling but irritating skin infections than for making people desperately ill. Our formidable immune system and torrid body temperature, too high for most fungi to tolerate, ensured that people in good health generally shook off serious attacks.
C. gattii is different. Until it emerged on Vancouver Island, it had occasionally sickened healthy people elsewhere but had never before caused an outbreak—a burst of unexpected infections. Its appearance in Canada seemingly also marked a jump into new territory with a much cooler climate, where the microorganism had inexplicably become more harmful. Between the outbreak's start and the end of 2012, 337 British Columbians were reported infected, of which two thirds were Vancouver Island residents, says Eleni Galanis, an epidemiologist at the British Columbia Center for Disease Control. And by 2005 C. gattii had started making people sick farther south, in the U.S. Pacific Northwest. Since then, at least 100 people in that area have been infected, and 25 to 30 percent of them have died. “It's a fairly high mortality rate for an environmentally acquired fungus,” says Joseph Heitman, director of the Center for Microbial Pathogenesis at Duke University. For the most part, although these are not AIDS patients, about half had weakened immune systems from prescribed drugs or illness, and many of the rest had common ailments that can weaken immune systems to a lesser extent, such as diabetes, or lung, kidney or heart disease. But 20 percent or more were healthy prior to infection. “Many of these patients were completely healthy, spending a lot of time outdoors, and suddenly they were very ill,” Heitman adds.