The Pacific Northwest is seeing a new infection that previously affected mostly people in tropical and subtropical regions. Another effect of global warming? Could be.
The offending organism, Cryptococcus gattii, is a relative of the more common Cryptococcus neoformans, which is present worldwide and affects mainly people who are HIV-positive or otherwise immune suppressed. In contrast, C. gattii mostly affects those with healthy immune systems. Following a larger outbreak in Canada, there have been a total of 60 human reported cases in 4 states (California, Idaho, Oregon, and Washington) since 2005, according to a new report from the Centers for Disease Control and Prevention (CDC).
Symptoms of the disease—which arises from inhaled spores or yeast forms that enter via the respiratory tract and then spread—include cough, headache, difficulty breathing, nausea, fever, and weight loss. Among the 60 reported cases, 57% had pneumonia and 43% had meningitis. Of 45 for whom the outcome was known, 9 died.
“This looks like a hypervirulent strain of cryptococcus that’s different from the one we’re used to seeing,” infectious disease specialist Dr. Christopher J. Harrison told me in an interview.
He said that although “I wouldn’t be looking around every corner for it,” C. gattii should be considered in any patient with atypical pulmonary infiltrate or nodules and central nervous system symptoms and who lives in the Pacific Northwest or who has traveled there recently.
Unfortunately, routine laboratory tests don’t distinguish between the two cryptococci. Amphotericin, the antifungal recommended to treat C. neoformans, is also recommended for C. gattii, but no clinical trial data exist. “We really don’t have solid evidence on the optimal treatment,” said Dr. Harrison, of Children’s Mercy Hospitals and Clinics, Kansas City Mo.
Should we be worried? “It’s always worrisome when a pathogen gets outside its previously normal geographic area and produces disease out of proportion to what we expect, because it means there’s something genetically different…It says that these organisms are adapting in a way that’s not good for the humans that they come into contact with.”
The CDC is continuing to monitor C. gattii through a formal surveillance system, and is conducting further studies.
—Miriam E. Tucker (@MiriamETucker on Twitter)