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[Stigmata]

Not a threat, so long as nobody utters the phrase "Ph'nglui mglw'nafh Cthulflu R'lyeh wgah'nagl phlegm".

 

[dfc05]

Mammals. Mammals and birds. Mammals. Mammals. Mammals with insect vectors.. Mammals with insect vectors. Mammals with insect vectors.

You may not have noticed my point but it becomes progressively rarer for a pathogen to affect different species the less closely related they are. You find a bunch infecting various mammals and only a very rare few viruses which affect different classes (such as flu) though even then they need to mutate and/or cross with different related strains.

Pathogens need to be adapted to their host prior to the host needing to adapt immunity to them. One does not simply walk into a host organism.

Ah, ok I see now you're talking about making two different species both sick. I just find it more pertinent to this scenario that the pathogen wouldn't necessarily "need to be adapted" to a new host in order to live and thrive within it, as they can already have that functionality within disparate species regardless of whether they've seen the new host before. Also, we might consider invasive species -- maybe it thrives in the new environment, even so much that it outcompetes all the native species which have been there long before the new guy came around. If some bug in that lake got into a human, maybe it would be like "hey it's warm in here and look at all these nutrients, I'm so happy! nom nom nom." Not totally impossible unless their home lake is, say, highly pressurized. In that case I guess they might just explode. Who knows. But you can't just totally discount the possibility of a newly discovered species being pathogenic.

 

[Maestro]

Extremophiles of the type likely to survive in a subglacial lake are very unlikely to have enough in common to infect us, I think. Sure, there are microbes that survive at the sea floor, but when we bring them to surface we could pretty much bath in them due to the fact that they just can't function in our environment, having adapted so heavily to one that is completely different.

It's possible, but I think astronomically unlikely.

 

[Eejit]

Ah, ok I see now you're talking about making two different species both sick. I just find it more pertinent to this scenario that the pathogen wouldn't necessarily "need to be adapted" to a new host in order to live and thrive within it, as they can already have that functionality within disparate species regardless of whether they've seen the new host before.

Pathogens surviving and thriving within their host is what makes the host sick.

Occam's razor agrees with biological science. If the vast majority of pathogens can only affect one or a small handful of closely related species and most hosts are only affected by a tiny minority of the total number of pathogens globally it follows that this is because the pathogen has adapted to these organisms rather than the host having evolved resistance to all others.

A pathogen does need to be adapted to its new host. There's a lot of research examining how zoonotic diseases became much more common as we domesticated animals and began to live in close proximity to them.

You forget we have a lot of non-specific biological, basal defenses. You have to make the qualifying heats before you can join the host-pathogen evolutionary arms race.

Also, we might consider invasive species -- maybe it thrives in the new environment, even so much that it outcompetes all the native species which have been there long before the new guy came around. If some bug in that lake got into a human, maybe it would be like "hey it's warm in here and look at all these nutrients, I'm so happy! nom nom nom." Not totally impossible unless their home lake is, say, highly pressurized. In that case I guess they might just explode. Who knows. But you can't just totally discount the possibility of a newly discovered species being pathogenic.

It's not just pressure that might kill an organism in a new environment. Too many nutrients can be toxic. Different osmotic pressures (very likely in this case) can also cause explosions. Different amounts and kinds of free radicals. If they're not adapted to a higher temperature they won't be able to take advantage of it to reproduce quickly the way native flora can, their enzymes will have evolved to operate at highest efficiency at low temperatures. A large portion of their metabolism will be dedicated to producing anti-freeze compounds. Given the environment any bacteria present are likely to be lithotrophic.

 

[Maestro]

Yes, what Eejit said.

 

[dfc05]

Well, that is pretty convincing

Playing devil's advocate/digging myself into a hole, I'd still contend that sometimes "life will find a way" and there are counterexamples of biota that normally spend their entire life cycle happily hanging out in lakes or rivers, but can sometimes cause disease if a human happens to encounter it. Mostly it irks me that there are some things that, as far as we know, are truly impossible (like breaking the laws of thermodynamics), and I'd consider something like bacteria being able to cause disease in an organism outside its native environment to be improbable, but not impossible.

 

[Eejit]

If you mean disease like getting the shits, vomiting etc then sure, a bunch of random bugs could do that alright.

 

[Maestro]

I think Eejit means Ebola or Gonorrhea, those are pretty heavily adapted to kill us effectively. E. Coli gut infections happen all the time, but pass right through due to the irritated bowels in question ejecting it and its toxins.