A list of some strange things about Candida Auris.
1) It arose in at least five different areas of the world at about the same time.
2) it occurs more often near large bodies of water, which suggests its natural reservoir may be a water animal *or plant*, as with some related fungi.
3) It can live at temperatures much higher than other related fungi, suggesting the natural reservoir may be a bird.
4) It has less visibility to parts of the immune system than similar fungi.
5) It has quickly developed resistance to many anti fungals. This may be in part because it was in people who were being treated for something else, and it survived the course of treatment. It also may have reverted to a form that evolves quickly, in order to compenste for the loss of access to a symbiotic bacteria with which it was paired. It's current 'fast evolving' form allows it to 'learn' genetic resistance from other organisms around it, including other species.
6) It is very difficult to diagnose without sophisticated equipment, even in developed countries. This suggests there may be numerous additional 'clades' or strains along coastal Africa, Asia and Latin America.
7) It can assimilate genetic information in unusual ways, and overlapping strains may 'share' genetic information involving anti fungal resistance and other things.
8) Candida auris is more sensitive to acids than closely related species of fungi, which could suggest it is used to surviving in the ocean.
Probable origin of C auris.
Candida auris probably had a stable host for thousands of years, or longer.
Several hundred years ago, or more recently, that host probably declined substantially or went extinct, and C auris re established populations in new host colonies.
Sometime around 2000 to 2005 those new host populations probably began to go extinct and C auris began looking for new hosts, which has led to its spread to humans.
C auris's original host colony was probably maintained between an amphibian or aquatic plant and a bird. That mean the original population lived between those two species symbiotically.
Once the amphibian went extinct C auris shifted its reproduction method, which reverted some of its characteristics to an earlier genetic period, giving it the ability to adapt and evolve faster.
The fact that humans have 'some' relationship to the decline or extinction of at least two ancestor host species probably is organically 'visible' to C auris in a sort of evolutionary way.
In other words humans and C auris probably fill competing niches in a way at this point.
That would explain why C auris, in its currently 'reverted' neotenous phase is most virulent in humans who are near death. It's next step viz humans, if it does not find a new host pair, will be to increase virulence dramatically. In other words if the total population of C auris declines to where the existence of its species would benefit from a population explosion, it's 'evolution' will intelligently seek a way to rapidly spread at the expense of organisms, e.g. humans, which do not provide a host environment nor bring it closer to a host environment.
If C auris successfully uses humans to find 'a second half of a host colony' then it would move forward genetically, its neotenous reversion would disappear, and it would develop new functions.
The specific niche that C auris is trying to use humans to fill is probably that of an extinct amphibian.
The only way humans could fill that role would be if the first part of the host, e.g. migratory bird, fed on humans, or if the part of the relationship which swans fulfill transfers to another species that humans eat.
In the latter case Candida auris would not become less virulent, it would simply become another factor associated with death in humans, but its virulence would stabilize.