'Highly virulent' fungus spreading among humans, animals

May 07, 2010
Portland, Ore. -- A "highly virulent" strain of the fungus Cryptococcus gattii is spreading in the Pacific Northwest and infecting both humans and animals, according to a recent study. But Oregon's public health veterinarian and one of the study's co-authors say media reports have exaggerated the threat of the rare fungal infection.

"It's not the fungus that's going to kill the Pacific Northwest," says Emilio DeBess, DVM, Oregon's Public Health Veterinarian. "It's rare."

DeBess says only roughly 60 cases total have been diagnosed since 2004.

Robert Bildfell, DVM, DACVP, has been working with samples from infected animal hosts at Oregon State University's veterinary diagnostic lab. He says the media interest in the story is exaggerated.

"The degree of panic that has been generated is not appropriate at all," Bildfell says. "This is not the scourge that has been portrayed."

The recent study from three researchers at Duke University published in the April 2010 issue of PLoS Pathogens points out that the new isolates of the fungus are "highly virulent" and affecting otherwise healthy hosts. However, the study only counts 39 cases from 2005 to 2009 (18 human and 21 animal, including a bottlenose dolphin in San Diego).

The fungus is rare and typically affects immunocompromised hosts, but can be fatal. Bildfell has seen emaciated elk struck down by the disease, but he wonders about the cause. "It's a bit of the chicken and the egg," he says: Were they sick to begin with, or did the fungus do them in?

According to Bess, healthy humans and animals may be affected in as many as 20 percent of infections, but long-term regimens of antifungal medications in humans and animals fight off the fungus.

"[T]he major concern is and continues to be the inexorable expansion throughout the region," write the researchers. The most virulent strain of the fungus appeared first on Vancouver Island in Canada in 1999, then spread from 2003 and 2006 to British Columbia and Washington and Oregon from 2005 to 2009. Isolated cases in Mexico and Southern California related to travel indicate that Northern California is next, say researchers.

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