Cryptococcus gattii

Cryptococcus gattii, formerly known as Cryptococcus neoformans var gattii, is an encapsulated yeast found primarily in tropical and subtropical climates. Its teleomorph is Filobasidiella bacillispora, a filamentous fungus belonging to the class Tremellomycetes. C. gattii causes the human diseases of pulmonary cryptococcosis (lung infection), basal meningitis, and cerebral cryptococcomas. Occasionally, the fungus is associated with skin, soft tissue, lymph node, bone, and joint infections. In recent years, it has appeared in British Columbia, Canada and the Pacific Northwest. It has been suggested that global warming may have been a factor in its emergence in British Columbia. From 1999 through to early 2008, 216 people in British Columbia have been infected with C. gattii, and eight died from complications related to it. The fungus also infects animals, such as dogs, koalas, and dolphins. In 2007, the fungus appeared for the first time in the United States, in Whatcom County, Washington and in April 2010 had spread to Oregon. The most recently identified strain, designated VGIIc, is particularly virulent, having proved fatal in 19 of 218 known cases. C. gattii has recently been divided into five species. These are C. gattii, C. bacillisporus, C. deuterogattii, C. tetragattii, and C. decagattii. Cryptococcal disease is a very rare disease that can affect the lungs (pneumonia) and nervous system (causing meningitis and focal brain lesions called cryptococcomas) in humans. The main complication of lung infection is respiratory failure. Central nervous system infection may lead to hydrocephalus, seizures, and focal neurological deficit. Soil debris associated with certain tree species has been found frequently to contain C. gattii VGIII MATα and MATa, and less commonly VGI MATα, in Southern California. These isolates were fertile, were found to be indistinguishable from the human isolates by genome sequence, and were virulent in in vitro and animal tests. Isolates were found associated with Canary Island pine (Pinus canariensis), American sweetgum (Liquidambar styraciflua), and Pohutukawa tree (Metrosideros excelsa). Leading up to the study one of the authors, Scott Filler, sent his daughter Elan to obtain and culture fungal samples in the greater Los Angeles area; one of these turned out to be C. gattii. Her work was presented at the Los Angeles County Science Fair, and she was credited as an author on the publication. Lead author Deborah Springer said, 'Just as people who travel to South America are told to be careful about drinking the water, people who visit other areas like California, the Pacific Northwest, and Oregon need to be aware that they are at risk for developing a fungal infection, especially if their immune system is compromised.' The highest incidences of C. gattii infections occur in Papua New Guinea and Northern Australia. Cases have also been reported in other regions, indicating its spread to India, Brazil, Vancouver Island in Canada, and Washington, and Oregon in the United States. Unlike Cryptococcus neoformans, C. gattii is not particularly associated with human immunodeficiency virus infection or other forms of immunosuppression. The fungus can cause disease in healthy people, potentially due to its ability to grow extremely rapidly within white blood cells.