OREGON STATE UNIVERSITY

Oregon State Researchers Monitoring Potential Spread of Fungal Disease

02/20/2009

CORVALLIS, Ore. – A fungal organism called Cryptococcus gattii, which caused a disease outbreak among humans and animals on Vancouver Island 10 years ago, may be showing signs of emerging in other areas of the Pacific Northwest, including Oregon.

Since the 1999 outbreak in British Columbia, which affected more than a hundred residents, sporadic cases of C. gattii infection have been reported in the Northwest – but most of the people involved had ties to Vancouver Island.

However, during the past two years, pathologists at Oregon State University’s Veterinary Diagnostic Laboratory have identified C. gattii in about a half-dozen animals from Oregon or just off the coast, including a dog, cat and porpoise – none of which had apparent ties to British Columbia.

“Cryptococcus has been around forever and it’s not that unusual, but the C. gattii that was associated with Vancouver Island was a different, far rarer strain that is endemic to Australia and Southeast Asia,” said Rob Bildfell, an associate professor in OSU’s College of Veterinary Medicine. “It’s been a bit of a surprise to find it here in the Pacific Northwest.”

According to the Centers for Disease Control and Prevention, cryptococcosis is a disease that originates from the Cryptococcus fungus. The most common type, C. neoformans, typically infects persons with compromised immune systems, including infants, the elderly, persons with HIV and others. The emergence of C. gattii concerns health officials because it can cause infections in healthy individuals as well.

Symptoms in humans include infection that may cause pneumonia-like illness, characterized by shortness of breath, coughing and fever, according to the CDC. Skin lesions may occur and severe cases may lead to meningitis. More information on the condition is available at: http://www.cdc.gov/nczved/dfbmd/disease_listing/cryptococcus_gi.html.

Infection is thought to occur through airborne transmission and not person-to-person, animal-to-animal, or animal-to-person, officials say.

In Australia, the fungal organism was found most commonly in eucalyptus groves, which are not exactly prominent in the Northwest. The preferred habitat on Vancouver Island seemed to be in forests that had numerous alder, cedar and Douglas-fir trees, said Bildfell, who specializes in wildlife diseases.

“Based on the increased cases, it’s probable that C. gattii is spreading,” Bildfell said. “It’s possible that we’re finding it more now because we’re looking for it, but cryptococcosis in dogs is unusual, as is fungal disease in porpoises. It’s very distinctive and likely would have been noticed before.”

Bildfell and Beth Valentine, also a pathologist in the OSU Veterinary Diagnostic Lab, are co-authors of a 2009 paper published in the Journal of Veterinary Diagnostic Investigations that outlines the pathological investigation of a dog from Salem that became infected with C. gattii and died. In another forthcoming article, Bildfell and co-authors characterized the genetics of Oregon isolates and found there were three different strains of the organism.

Symptoms for animals infected with C. gattii may vary, depending on where the infection is located.

“In cats, Cryptococcus usually colonizes the nasal area and can cause nasal discharge or even a small nasal mass, leading to mild breathing difficulty,” Bildfell said. “If the infection reaches the lungs, their breathing will be labored. Cryptococcus can also localize in different organs of the animal, especially the brain. Clinical signs in such cases could range from blindness to seizures.

“We’ve seen Cryptococcus primarily in cats, but it’s now being found in dogs and even camelids (alpacas and llamas),” Bildfell added. “In general, the fungus doesn’t like dry climates, so it tends to be more of a problem in the western portion of the Pacific Northwest.”