Fungus Alert: Cryptococcus Gattii
How a silent fungal foe has infiltrated our forests.
If you read my post on climate change and the emergence of new fungal threats, you may have been worrying over the possibility of a new fungal enemy. I’m writing this today to tell you that you may have been right to worry. In the original post, we focused on the emergence of Candida Auris, a nasty fungal infection which popped up in people’s bodies all over the world all at once, due to rising global temperatures training the fungus to survive in the human ecosystem. This time, I want to alert you to the recent emergence and spread of one Cryptococcus Gattii, and advise you on what to do in the face of a fungal invader with a 13-33%% mortality rate upon infection.
Our story starts in the old growth forests of the pacific northwest, a place that is particularly fond to me, and known the world over for it’s natural beauty.
All may seem at peace in the forest, but change is happening in these quiet and misty groves. Known for the growth of trees that are truly gargantuan in size, the stable and nurturing environment of the pacific northwest has recently been in a state of flux.
Wildfires, droughts, and heatwaves have regularly rocked the area to it’s core, with the most recent bout this summer seeing temperatures reaching peaks of 145 degrees Fahrenheit (63 Celsius!). It’s estimated that more than 1400 people died as a result of the heat. This was exacerbated by the fact that many homes and buildings in the region were not equipped with air conditioning. The heat sparked multiple wildfires, which displaced thousands of people, reduced agricultural yields, and buckled some roads and bridges to the point of closure. The smoke from the wildfires dyed the skies blood red, all in the midst of the COVID-19 pandemic. But these horsemen-esque disasters are not the focus of our story.
Amongst the chaotic change of the past few decades, an invasion of silent killers has been establishing itself in the forests of the pacific northwest. Originally endemic to the coasts of Australia and New Zealand, Cryptococcus Gattii is a fungus that grows in the soil around tree roots. As the climate of the pacific northwest has changed, multiple parallel emergences of new C. Gattii strains have occurred in our forests.
When humans walk through an infected forest, we inhale spores of C. Gattii into our lungs. Unlike it’s cousin Cryptococcus Neoformans, it infects people who have otherwise healthy immune systems. When C. Gattii made the jump from it’s native Australian ecosystem to that of the pacific northwest, people started falling ill. The onset of symptoms could occur many weeks or months after exposure, and run a long list, centered around lung and central nervous system involvement:
Prolonged cough (lasting weeks or months)
Sharp chest pain
Shortness of breath
Sinusitis (cottony drainage, soreness, pressure)
Severe headache (meningitis, encephalitis, meningoencephalitis)
Stiff neck (prolonged and severe nuchal rigidity)
Muscle soreness (mild to severe, local or diffuse)
Photophobia (excessive sensitivity to light)
Blurred or double vision
Eye irritation (soreness, redness)
Focal neurological deficit
Fever (delirium, hallucinations)
Confusion (abnormal behavior changes, inappropriate mood swings)
Nausea (with or without vomiting)
Skin lesions (rashes, scaling, plaques, papules, nodules, blisters, subcutaneous tumors or ulcers)
Having never encountered the fungal infection before, doctors in the region told many C. Gattii victims that they had developed lung cancer, based on radio-imaging showing foreign masses in the lungs. When they finally did figure out the culprit, they contacted their Australian counterparts and compared data. It was found that C. Gattii infections had nearly a 10x higher mortality rate when patients in the pacific northwest encountered the adapted variant as compared to Australian patients and their endemic variety.
But why was C. Gattii such a deadly and lengthy illness for those who contracted it? The answer lies in evolution and the environment. Because C. Gattii had evolved in contact with many soil amoebas, it was already adapted to fight human white blood cells extremely well, and can even reproduce within macrophages like white blood cells. Both are eukaryotic, and attack their prey via phagocytosis, wherein the amoeba or white blood cell engulfs the bacteria or fungi and attempts to digest it.
Similar to the phenomenon we observed in Candida Auris, whereas the internal temperature (resting and during fever) of our body would normally protect us in tandem with an immune response, this has become less effective as the environmental C. Gattii strains have adapted to be able to survive spikes of high temperature in the environment. People infected with C. Gattii need at least 6 months of treatment, and once masses form in the lungs or the brain, they often require surgical removal, which can be very risky in the case of a person with an immune system weakened by infection.
Unfortunately, C. Gattii is not something I think we can hope to contain to the forests of the pacific northwest. In our globalized world, the high temperature adapted strains of C. Gattii are bound to spread to other environs, and have begun to do so already. Forests in Louisiana, Alabama, Georgia, Michigan, and Nevada are thought to likely harbor C. Gattii. Even if we could contain C. Gattii exclusively to the forests we think it occupies, there are many other fungi filling similar niches in soils all around the world, which will all experience environmental changes as the result of climate change. Members of the Cryptococcus species complex exist in soils all around the world, and these are likely just the tip of the iceberg of unknown fungal foes.
This is probably not a disease that will kill hundreds of millions, as it has not yet been observed to spread from person to person. However, it will make experiencing our forests more risky, and that has larger implications than one might think. The U.S. is graced with a wealth of beautiful parks, and personally, they have been one of the greatest boons to my physical and mental health and wellbeing. We may be coming to the end of a golden age of forests that we didn’t even know we were in, and it may be that wearing a mask even in the forest becomes a wise choice. (I hope not, the smell of the forest is near-holy to me).
I’d like to end with an air of optimism. There are tons of scary things out there, but it has only been in the last few hundred years that we have gained the ability to know them, and even fewer that we have gained the ability to fight them. Some of the best and brightest minds work every day to combat emerging problems like this, and I wouldn’t be able to write this post without them. Although the COVID-19 pandemic has put a damper on my confidence in governments to implement changes as necessary, it has strengthened my confidence in our scientific community to quickly find solutions to our biggest threats, and I believe that as information becomes more easily disseminated, we can overcome any problem.
In the meantime, get out and enjoy nature! Despite the risks, it’s still a net positive to get back down to earth, and breathe some fresh air, just maybe not too deeply.
If you liked this post, you’re in luck! This is a follow up on a previous post, which you can read here.
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