EMERGING MALADY: Infections caused by Cryptococcus gattii, pictured in the above microscope image, are on the rise in the Pacific Northwest, experts warn.
Image: Washington State Department of Health
A deadly infectious disease once thought to be exclusively tropical has gained a toehold in the Pacific Northwest, and health experts suspect climate change is partially to blame.
Last week the CDC issued a report warning U.S. doctors to be alert for patients showing signs of a cryptococcal infection.
The infection is spread by a fungus, Cryptococcus gattii, that attacks the nasal cavity and spreads to other body sites, causing pneumonia, meningitis and other lung, brain or muscle ailments. The disease also affects animals.
Until 1999 most human cases were limited to Australia and other tropical and sub-tropical regions, including Asia and Africa, along with parts of southern California.
But in 2004 the first case was reported in Oregon, and as of July 60 cases in the Pacific Northwest have been reported to the Centers for Disease Control and Prevention. Of the 45 cases in the region with known outcomes, nine patients died because of the infection and another six died with it, the CDC reported.
"This is not insignificant. These people died," said Dr. Ted Schettler, science director for the Massachussetts-based Science and Environmental Health Network, a group that advocates for the use of science in policy decisions.
"When I went to medical school many years ago, Cryptococcus was a rare pathogen," he added. "If you saw it in a patient, it was someone who was immuno-compromised. Here now you're seeing it in the Pacific Northwest – where you wouldn't expect to see it – in people who wouldn't normally be sick."
The CDC alert stressed that other factors could be at play in the disease's spread besides climate change: The fungus may have adapted to a new climate niche, or environmental conditions favorable to C. gattii might be broader than suspected.
Oregon epidemiologist Emilio DeBess, also the state veterinarian, cautioned against drawing direct links to climate change. "The answer is we really don't know," he said. "We need to step back a little bit and find out how diverse is this organism. That's going to tell us about the age – did it just show up or has it been here a long time."
But the CDC report notes that epidemiologists have ruled out increased disease awareness and reporting. And its emergence fits with the redistribution of infectious diseases predicted by various climate models, Schettler said.
"It's very consistent with the literature," he said. "It appears this was a pathogen finding a new home. It is just sort of interesting to put this alongside other parameters of climate change."
There are other recent examples of tropical pathogens exploiting newly hospitable ecosystems.
Last week the CDC issued a bulletin on a dengue fever outbreak in Puerto Rico, noting that while the disease is common on the island, the most recent epidemic is large and started earlier than usual.
Last year health researchers concluded warmer temperatures, higher humidity and increased precipitation – the types of weather forecast as greenhouse gas concentrations increase – have triggered higher rates of West Nile virus infection across the Western United States.
And researchers at the University of Arizona suspect hotter temperatures and more intense dust storms are propelling an epidemic of Valley Fever across the Southwest.
DeBess was careful to put the Northwest's C. gattii outbreak in perspective. Only 60 cases have been detected over nearly six years in two or three states. Meanwhile 36,000 people die annually in the United States from influenza.
"It doesn't mean we are't paying any attention," he said. "But you have to make your own decision: Do we worry about C. gattii, or do we worry about influenza more?"
DailyClimate.org is a nonprofit news service covering climate change.
More Food from Fungi? Crop-Enhancing Microbes Challenge Genetic Engineering
13 Comments
Add CommentThis line of reasoning makes perfect sense if the Pacific Northwest now has a tropical climate. Otherwise this is smells like more global B.S.
Reply | Report Abuse | Link to thisNot that the expanded risk should be ignored. The spread of these diseases could be due to increased travel or shipping from tropical regions, for example.
That is, unless disease agents are planning in advance for the upcoming climate changes that will be produced by global warming. Perhaps they read Scientific American.
Right on, like other species migration due to human trafficing can be explained as the culprit. In the nothern hemisphere in Europe 10's of thousands of Smaller size Parrots in the wild have addopt to the colder weather and becoming a pest for the farmers. The tropical birds escapies counted only about a hundred 30 years ago. Virusses, etc have been known to travel accross continents with bird migration, human airtravel and even tropical storms. Its all connected, We love to put a finger on cause and the problem as fast as possible and disregard all other possibilities. We might get it wrong or stay confused, we can have that.
Reply | Report Abuse | Link to thisCome on now! President Bush said that global warming is a hoax. Since President Bush is the decision maker and correct about everything, then that disease is also a hoax cooked up by some "Gore Tree-huger."
Reply | Report Abuse | Link to thisIt doesn't matter if that disease can travel and thrive in tropical like climates...just wait until winter and the disease will freeze to death when the North west temps. drop.
I think there is a possibility that climate change is involved. But note I said "possibility". It still needs to be proven, and I think over time we'll see if climate change is the actual trigger for the increased spread of cryptococcal disease in the northwestern United States. I agree with jtdwer that increased travel and/or shipping from tropical regions could be one of the causes. Fortunately, there's a growing awareness of the presence of cryptococcal disease in the U.S. as it stands a better chance of being diagnosed when a person becomes ill with the symptoms.
Reply | Report Abuse | Link to thisScience is too important to be left to people who are scientifically literate.
Reply | Report Abuse | Link to thisThere already is rainforest in the Pacific Northwest.
Reply | Report Abuse | Link to thisCrystal - Good point, and I think generally very humid with frequent precipitation. As I understand, it's also not very seasonal, although all this is relative. I could be wrong, but I expect that the typical seasonal temperature variability still exceeds any increase that has so far been imparted by global warming.
Reply | Report Abuse | Link to thisThe high humidity would generally make regional conditions favorable for fungi development. The article states:
"Until 1999 most human cases were limited to Australia and other tropical and sub-tropical regions, including Asia and Africa, along with parts of southern California."
Neither Southern California nor the Pacific Northwest are generally known for their sub-tropical rain forest environments.
Could be that increased travel in these regions has resulting in increasing contamination of spores. Customs checks inbound passengers for fruit, but not spores.
While I can see why climate change would cause tropical diseases to move to higher latitudes, the uncertainty in this case (since several other things may account for it), makes the title of this article misleading. I'm starting to wonder if Scientific American is mis-titling articles on purpose to start fights in the comments sections, since that is usually what ends up happening. I even see them having a motivation to do so: while they listen to the mainstream scientific community and accept anthropogenic global climate change as real and dangerous, they know many people do not, and starting fights between them and other readers allows the editors to see what the other side really thinks, and maybe points out studies or arguments that need debunking.
Reply | Report Abuse | Link to thisFirst off, the author is not dismissing the fact that the connectedness of the world is playing a factor here. It is a case of multiple factors, climate change being "partially" to blame. You can bring a cactus to New England, but deciduous or evergreen trees will out complete it. CAM plants are not built to excel in that climate. Same goes for this pathogen. The fungus needs a certain threshold temperature to survive. It has found a temperate rainforest, with increasing temperatures, and now its spores are able to procreate.
Reply | Report Abuse | Link to thisThis fungus may have been brought to this country many times but was unable to survive a long winter or summer temperatures were not hot enough to bring it out of a dormant state for long enough. Climate may be a factor but not the whole story and the author made that clear.
The title of the article is somewhat sensational and is probably done on purpose to attract readers. I'm sure for Mr. Fisher that was motivation enough. He at least could have put "may" be linked to climate change but technically he is not lying.
The subtitle is contradicted by the article itself: 60 people in the PNW got the disease; only 9-15 died of it, not 60.
Reply | Report Abuse | Link to thisThere isn't near as much rain forrest left as there used to be. I guess the conservatives will plan to cure the problem by letting all the trees be chopped down and given to japan for next to free and sold back to us like they did back in the reagan years.
Reply | Report Abuse | Link to thisrdlyons - Good catch! The article states:
Reply | Report Abuse | Link to this"But in 2004 the first case was reported in Oregon, and as of July 60 cases in the Pacific Northwest have been reported to the Centers for Disease Control and Prevention. Of the 45 cases in the region with known outcomes, nine patients died because of the infection and another six died with it, the CDC reported."
I carefully interpret this statement to indicate that there have been 60 cases reported in the Pacific Northwest in the period from 2004 to 7/2010; 15 cases have not yet had any known outcome; six died while they had the disease; 9 died as a direct result of the disease.
Ken216 - Fair assessment, but a frequent reader will know that the sensational, slightly exaggerated title has become standard fare for SciAm, especially when the active ingredient is Global Warming.
While the author clearly indicated that there were other potential factors involved in the spread of this disease, it was only after stressing global warming in the title and opening paragraph. One might even imagine that the editor had returned the article to the author with instructions to 'beef up the climate connection'.
While adequate environmental conditions may have long been available for this fungi in the Pacific Northwest, there have been significant changes in its potential transfer.
Since the 1990s international airline routes have been dramatically opened up to competition, lowering prices and significantly increasing the number of international air passengers and cargo shipments. The international exchange of people and products has coincidentally increased the potential for rapid international exchange of microbes and spores.
This potential explanation for the appearance of foreign diseases is more likely, at this point, than global warming. The increase in international exchange has already been researched as a potential risk in the spread of bird flu and other active infections where exposure prior to patient death is necessary and can be achieved by air travel. In the past, a ship full of plague casualties could be turned away from port.
Global warming sensationalism.
Reply | Report Abuse | Link to thisThe headline is a reach, considering at best there is a possible link, and the subtitle is pathetic! It's a huge overstatement of the actual deaths, while sounding as if it is so far this year: "as of July", 60 people have died.
The titles are designed to grab people's attention, and I hardly think it's accidental about the number mix up. What kind of writer would make a mistake like that in their subtitle? A sensationalist writer would, but not by mistake.
Of course the obviousness of the mistake in the subtitle could just be a ruse to distract people from considering the assertion made in the main title.
But hey, whatever increases the number of hits on a page is good for the advertisers, right?