More than a decade ago, a fungal species called Candida auris was discovered in the ear canal of a 70-year-old Japanese woman at Tokyo Metropolitan Geriatric Hospital. This fungus can cause fatal infections in risk groups and can now be found worldwide, causing outbreaks in five continents.
Emerging Fungal Pathogen
Over one billion people around the world have contracted fungal infections, while 1.6 million people are dying as a result. To further understand this threat, molecular biologist Auke de Jong conducted research that focuses on the nature of Candida auris.
It has been observed that infections caused by Candida species have shifted away from being easily treatable to being drug-resistant. Surprisingly, Candida auris has been among the most notorious infectious fungi species.
The origin of this pathogen is still shrouded in mystery, so De Jong looked for cues in its DNA and behavior. He suspected that seawater plays a key role since this fungus has a very high salt tolerance, a substance many fungi cannot cope with. This means that the sea could be a likely route for the global spread of Candida auris, where the currents might have spread across it.
In his dissertation entitled "Fungal Pathogens Exposed. Novel insights into Candida auris and emerging relatives of the Candida haemulonii species complex", De Jong described the consequences of the rapid spread of Candida auris. According to him, this species causes an infection that cannot be properly treated, leading to an exceptionally high death rate among risk groups. Since it has a high tolerance for salt, it can also easily survive relatively high temperatures and common disinfectants.
Almost all infections from this fungus are contracted in hospitals since surgeries allow the pathogen to enter the patient's body. However, hospitals are unlikely to be the source, so it is still unknown where the patients first came in contact with it. Patients are believed to have already carried the fungus for some time.
On the other hand, its fast spread can be easily explained, mainly due to the medical advances in recent decades. In fact, there is currently a new group of people who continue to live with diseases from which people used to die more quickly. Its downside is that this group usually has a severely weakened immune system, making them much more susceptible to fungal infections.
Global Warming and the Rise of Super Fungus
In a separate study entitled "On the Emergence of Candida auris: Climate Change, Azoles, Swamps, and Birds," Dr. Arturo Casadevall and his team investigated the thermal tolerance of different fungi species. They suspected that something triggered the fungi to bubble up and cause disease, and they looked into the possibility of climate change.
Mammals are protected by a thermal restriction zone, making the difference between their basal and environmental temperatures. As the Earth becomes hotter due to global warming, the gradient between the two temperatures narrows. Higher environmental temperatures could likely lead to an increased adaptation to higher temperatures.
Most Candida species of fungi cannot tolerate the warmth of mammalian bodies, but it was found that Candida auris can grow at higher temperatures. The researchers conclude that its adaptation to hotter temperatures could have led to its emergence.
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