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epiTRENDS
Cryptococcus gattii: an Emerging Pathogen in the Pacific Northwest
February
2007 Vol. 12, No.
2
In 1999, Cryptococcus gattii was recognized as an emerging infectious disease in the Pacific Northwest. The original introduction is unknown, but could have been imported trees, crates, or even bird migration. The fungus has spread from Vancouver Island to other regions of Canada and the Pacific Northwest. Vehicles and other movement by people likely contributed to the rapid dissemination. Rare but severe human and animal infections occurred in parallel. It is not yet known if the fungus will colonize our region permanently or cause only transient problems. Considering the diagnosis, obtaining appropriate tests, and promptly reporting cases will improve the understanding of this pathogen.
epiTRENDS
P.O. Box 47812
Olympia, WA 98504-7812
Mary C. Selecky
Secretary
Maxine Hayes, MD, MPH
State Health Officer
Jo Hofmann, MD
State Epidemiologist for
Communicable Diseases
Deborah Todd, RN, MPH
Managing Editor
Marcia J. Goldoft, MD, MPH
Scientific Editor
Initial Recognition of Emergence
Exposure to spores of the soil fungus Cryptococcus neoformans can cause severe disease in immunocompromised persons, particularly those infected with HIV. The brain, lung, and skin are the most commonly infected sites. Unlike C. neoformans, C. gattii spores can cause infections in persons with normal immune systems. Both severe neurological and pulmonary infections occur.
Until recently, C. gattii was considered to be a tropical or semitropical organism occurring only in areas such as Australia. It was not known to be present in temperate climates such as western Canada. The first animal and human C. gattii cases in Canada were identified and diagnosed in 2001 on Vancouver Island. When the agent was recognized in the region, other cases were retrospectively documented back to 1999. Infections were found as well in domestic animals such as dogs, cats, and horses. Several porpoises were also discovered to be infected.
Reported symptoms in humans include severe cough and shortness of breath. There may be other symptoms such as chills, night sweats, and loss of appetite. About a fifth of cases have meningitis. Smoking or treatment with steroids may be risk factors for infection. Based on visitors with specific exposure time in the region, the incubation period may be 2 to 11 months.
British Columbia made cryptococcal infection reportable in 2003. By 2005 there were 129 human cases and four deaths, all from Vancouver Island. This represents a high rate of infection compared to areas where C. gattii normally occurs. Some cases occurred among residents and visitors without immunocompromised status or existing medical condition. By 2005 three human and six animal cases were reported in the Vancouver Coastal and Fraser Health regions in Canada. None the case patients had exposures on Vancouver Island. One case was fatal. Exposures included yard work, landscaping, and tree cutting.
Investigation by a team of public health, academic, and veterinary researchers isolated C. gattii from trees, soil, water, and air samples taken from Vancouver Island. Subsequently, C. gattii was also isolated from environmental specimens obtained from British Columbia lower mainland.
During 2005 three cats living in Washington near the international border were diagnosed with C. gattii by histopathology. Neither animal had potential exposures in Canada. Environmental sampling near the cats’ home identified C. gattii from soil and tree samples. Two persons in Oregon were reported infected with C. gattii although with genetically different strains.
Human or animal infections with C. gattii are reportable in Washington State as rare diseases of public health significance. Cryptococcosis may present as sharp chest pain, unexplained prolonged cough, shortness of breath, fever, severe headache, and weight loss. A patient may present with meningitis or pneumonia. In animals, symptoms vary among species, but may include runny nose, lumps under the skin, and infection of the lungs and nervous system. Since animal disease exceeded human disease in Canada, veterinary reporting is a particularly important part of surveillance.
Diagnosis of Cryptococcus sp. is done by commercial labs, but speciation and genotyping of C. gattii can be done at the British Columbia Centre for Disease Control Laboratory. Genotyping is needed to determine if the organism is related to the BC outbreak.
Typing of the organism is done on a fungal culture. Testing for cryptococcosis can be arranged through the local health jurisdiction. Local health jurisdictions can contact Communicable Disease Epidemiology Section (206 418-5500) for assistance. Treatment for cryptococcal disease is specific antifungal medications. Routine antibiotics for bacterial infections are not effective. Because the fungus is present in the environment, there are no particular precautions that can be taken to avoid cryptococcal disease. Be alert for long lasting or severe symptoms. Seek early diagnosis and treatment.
Image courtesy of www.doctorfungus.org, copyright 2007Further information about Cryptococcus gattii is available at: http://www.cryptococcusgattii.ca/
Other references:
MacDougall L, Kidd SE, Galanis E, Mak S, Leslie M, et al. Spread of Cryptococcus gattii in British Columbia, Canada, and Detection in the Pacific Northwest, USA. Emerging Infectious Diseases Volume 13, Number 1–January 2007.
S. E. Kidd, F. Hagen, R. L. Tscharke, M. Huynh, K. H. Bartlett, M. Fyfe, L. MacDougall, T. Boekhout, K. J. Kwon-Chung, and W. Meyer. A rare genotype of Cryptococcus gattii caused the cryptococcosis outbreak on Vancouver Island (British Columbia, Canada). PNAS, Dec 2004; 101: 17258 - 17263.
MacDougall L, and M. Fyfe. Emergence of Cryptococcus gattii in a Novel Environment Provides Clues to Its Incubation Period. J. Clin. Microbiol. May 2006; 44(5) 1851-1852.
Public health officials in multiple states, with the assistance of the Centers for Disease Control and Prevention, are investigating a large outbreak of Salmonella Tennessee infections. As of February 15, 2007, 290 persons with the infection have been reported to CDC from 39 states including four cases in Washington. The outbreak has been prolonged and of low intensity. The first cases occurred August, 2006. Two closely related DNA patterns of S. Tennessee isolates have been associated with this outbreak.
Investigation has identified peanut butter as being consumed more often by ill persons than well persons and as statistically linked with illness. Evaluation is ongoing for additional information about the consumption habits of cases, the patterns of distribution of cases, and possible source of contamination.
For more information on this outbreak, refer to the CDC website: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_2007/outbreak_notice.htm
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