Fungus Cryptococcus gatti Threat to Healthy People
An airborne fungus called Cryptococcus gattii is making its way down from British Columbia to the coastal northwestern United States, and it appears to have a lethal agenda. C. gattii, which usually only infects individuals whose immune systems are compromised, is now attacking healthy people, and it has affected some animals as well.
The report on this potentially deadly strain of fungus appeared in the online journal PLoS Pathogens. Entitled “Emergence and Pathogenicity of Highly Virulent Cryptococcus gattii Genotypes in the Northwest United States,” the authors warn that C. gattii “causes life-threatening disease in otherwise healthy hosts and to a lesser extent in immunocompromised hosts.”
The study notes that the new genetically different strain recently found only in Oregon is highly virulent and that “further expansion into neighboring regions is likely to occur,” including Washington, Idaho, and California. Appearance of C. gatti in North America is worrisome, say the authors, because it is the “first major emergence in a temperate climate,” which indicates its possible expansion.
This is not the first article that has included alarming information about C. gattii. In August 2009, a report published in Emerging Infectious Diseases, entitled “Spread of Cryptococcus gattii into Pacific Northwest Region of the United States,” was authored by the Cryptococcus gattii Working Group of the Pacific Northwest. Its authors included experts from a wide range of institutions, including Johns Hopkins University School of Medicine, University of British Columbia, Duke University Medical Center, and the Centers for Disease Control and Prevention, among others.
The 2009 article noted that “Infections in the Pacific Northwest are caused by multiple genotypes, but the major strain is genetically novel and may have emerged recently in association with unique mating or environmental changes.” The authors warned that the fungus caused “substantial illness and death,” and that aggressive medical and surgical tactics were necessary to successfully manage the infection.
Infection with C. gattii causes symptoms about two weeks or more after individuals or animals have been exposed to the airborne spores. Once the spores are inhaled, they embed themselves in the lungs, colonize, and then spread throughout the body. Symptoms include persistent cough, pneumonia, sharp chest pains, shortness of breath, fever, weight loss, headache, and nighttime sweats. Meningitis can also occur.
Treatment includes intravenous antifungal medications for six to eight weeks, followed by up to six months of oral fluconazole. Thus far the mortality rate has been about 25 percent among the 21 cases evaluated in the United States. About three times that number of animals have been infected.
In the Los Angeles Times, Julie Harris of the mycotic diseases branch of the CDC explained that “We need physicians to be aware of this [C. gattii] and think about it when they see symptoms of infection.” So far C. gattii is a rare occurrence, but with climate change and the fact that the fungus is carried by the wind, and that it is impacting healthy people, who knows what the wind may blow our way.
Byrnes EJ et al. PLoS Pathogens 6(4): e1000850
Datta K et al. Emerging Infectious Diseases 2009 Aug.
Los Angeles Times, April 22, 2010