Since 1999, Cryptococcus gattii has emerged as an important pathogen of humans and animals in southwestern British Columbia. Cryptococcosis is a fungal disease found worldwide in human and animal populations. C. gattii has posed new diagnostic and treatment challenges to veterinary practitioners working within the recently identified endemic region.

Clinical cryptococcosis has been reported worldwide in multiple animal species. It is the most common systemic fungal infection in cats and is often described in dogs. Other domestic species diagnosed with cryptococcosis include ferrets, goats, llamas and alpacas, horses, sheep, and numerous species of birds. Koalas have been identified to have both clinical disease and subclinical infections. There are numerous reports of cryptococcosis in nonhuman primates and isolation of Cryptococcus spp. has been reported from other wild animals, including a fox, dolphins, a cheetah, and an eastern water skink.

In December 2004, a case of human C. gattii infection was reported in Oregon, associated with an outbreak on Vancouver Island and in mainland British Columbia, Canada. A second C. gattii case was reported in Oregon in 2005, and 12 more cases were reported in 2006 and 2007. In 2008, in response to the emergence of C. gattii in the United States, CDC, state and local public health authorities, and the British Columbia Centre for Disease Control (BCCDC) formed the Cryptococcus gattii Public Health Working Group.

During 1999, C. gattii began appearing in animals and humans on Vancouver Island and, beginning in 2004, among mainland British Columbia residents who had no exposure to Vancouver Island. By the end of 2007, a total of 218 human cases had been reported to BCCDC.

During January 1, 2004–July 1, 2010, a total of 60 human cases of C. gattii infection were reported to CDC in the U.S.: 43 from Oregon, 15 from Washington, one from California, and one from Idaho. Approximately half (54%) of the patients were male; patients ranged in age from 15 to 95 years, with the highest proportion of patients (45%) aged 50–69 years. Among 47 patients for whom such information was known, 38 (81%) had an underlying condition that might have predisposed them to infection.

Among the 45 patients in the U.S. for whom outcome was known, nine (20%) died because of C. gattii infection and six (13%) died with C. gattii infection; two of the nine who died from C. gattii infection had no predisposing condition. In addition to human cases, 52 veterinary cases (among cats, dogs, ferrets, sheep, camelids, elk, horses, goats, and porpoises) were reported to CDC from California, Hawaii, Oregon, and Washington.

Physicians and veterinarians should consider C. gattii as a possible etiology of infection when treating patients (particularly those who are HIV negative) who have signs and symptoms of cryptococcal infection, and should ask patients about recent travel to the Pacific Northwest, British Columbia, or other C. gattii–endemic areas. Physicians, particularly in the Pacific Northwest, should report suspected C. gattii infections and submit clinical isolates to their state health departments when requested.

Additional information

Emergence of Cryptococcus gattii— Pacific Northwest, 2004–2010

Clinical characteristics and predictors of mortality forCryptococcus gattii infection in dogs and cats of southwestern British Columbia