History in Canada
The Cryptococcus gattii microorganism (C. gattii) is a yeast that can be found in soil, trees, and bird droppings in certain temperate regions of British Columbia (Figure 1). When the spores of this yeast are inhaled, they can infect the central nervous system, lungs, and skin of humans and other animals (Figure 1, inset). The first outbreak of C. gattii on Vancouver Island occurred in 2001, but a retrospective chart review has traced Canadian cases of the disease back to 1999.1
Most people who come in contact with C. gattii do not become ill with cryptococcosis. The elderly and people who smoke or have diseases such as HIV or invasive cancer are at greater risk for cryptococcosis, though infections do occur in otherwise healthy individuals.2 For those who do become ill, symptoms can be mild or severe and can appear weeks or months following exposure (median time from exposure to symptoms is 6 to 7 months).3 Symptoms include chest pain, dry cough, shortness of breath, and weight loss.3
The incidence of C. gattii infection is relatively high in BC, with over 240 human cases and 360 animal cases reported between 1999 and 2008.4 The incidence of C. gattii infection from 1999 to 2003 was between 8.5 and 37.0 cases per million residents per year on Vancouver Island.5 This is greater than the incidence of C. gattii observed in Australia (0.94 cases per million residents per year) where C. gattii is endemic.6 As a Vancouver Island public health official noted in 2002, “We’ve got a new bug on the Island, and the likelihood is we’re just going to have to learn how to live with it”.7
- 1. Kidd SE, Hagen F, Tscharke RL, et al. A Rare Genotype of Cryptococcus Gattii Caused the Cryptococcosis Outbreak on Vancouver Island (British Columbia, Canada). PNAS. 2004; 101(49): 17258-17263. http://www.pnas.org/content/101/49/17258.abstract.
- 2. MacDougall L, Fyfe M, Romney M, et al. Risk factors for Cryptococcus gattii infection, British Columbia, Canada. Emerg Infect Dis. 2011;17(2):193-199. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204768/.
- 3. a. b. MacDougall L, Fyfe M. Emergence of Cryptococcus gattii in a novel environment provides clues to its incubation period. J Clin Microbiol. 2006;44(5):1851-1852. http://jcm.asm.org/content/44/5/1851.
- 4. Mak S, Klinkenberg B, Bartlett K, et al. Ecological niche modeling of Cryptococcus gattii in British Columbia, Canada. Environ Health Perspect. 2010;118(5):653-658. http://ehp03.niehs.nih.gov/article/info:doi/10.1289/ehp.0901448.
- 5. Hoang LM, Maguire JA, Doyle P, et al. Cryptococcus neoformans infections at Vancouver Hospital and Health Sciences Centre (1997-2002): epidemiology, microbiology and histopathology. J Med Microbiol. 2004;53(Pt 9):935-940. http://jmm.sgmjournals.org/content/53/9/935.long.
- 6. Chen S, Sorrell T, Nimmo G, et al. Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand. Australasian Cryptococcal Study Group. Clin Infect Dis. 2000;31(2):499-508. http://cid.oxfordjournals.org/content/31/2/499.long.
- 7. Bell J. ‘We’ll have to learn to live with it’: Mysterious fungus could reach Victoria but there’s little cause for alarm, say officials. Victoria Times-Colonist. Victoria. 2002; p. 1.