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Interesting-Month-56 t1_j93snu0 wrote

Reply to comment by fack_yuo in Why are fevers cyclical? by Key-Marionberry-9854

To add to this, from the perspective of someone with biology training but not medical…

It is entirely possible that this is an evolutionary response. Fevers kill the disease and, if they go on long enough, the host.

It makes complete sense that a cycling fever provides the most likely survival of the host and that individuals that don’t cycle fevers simply don’t survive.

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aphasic t1_j943j0f wrote

It's also worth mentioning that the human immune system is an insane rube goldberg machine where almost every pathway has multiple mechanisms of negative feedback regulation. It's almost universal that when your cells sense a cytokine produced by a viral infection, like interferon gamma, they respond to it (inflammation, fever, antiviral gene transcription, etc), but they also up-regulate genes that serve to dampen the cell's response to interferon. If you put a cell in a steady state amount of cytokine, it will usually have a strong initial response, followed by a damping of the signal. There are a lot of mechanisms by which this happens (down-regulating the receptor, up-regulating the inhibitors of the receptor, etc.)

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DorkRockGalactic t1_j94xkxv wrote

Chaos into order, via evolution.

It's like a core metaphor for everything we are and know.

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assidreemz t1_j953rl6 wrote

Yea it’s really cool to think about. Entropy is one of my favorite words.

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thechilipepper0 t1_j979hne wrote

I tried to explain it to an MFA once. It’s surprisingly difficult to describe in simple terms

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Felted_Grape t1_j9egi9o wrote

I like to imagine we are a little backwards swirl going to order in the grand big swirl pattern that overall tends towards entropy.

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DorkRockGalactic t1_j9gouep wrote

That's a good analogy really.

With all the random stuff happening, it's possible for things to order themselves by random chance. Earth life happened to order itself just the right way to self replicate and thrive on our island of stability where there are energy gradients to exploit.

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SavannahInChicago t1_j96u3o4 wrote

I am currently studying anatomy. Calling the body itself a rube goldberg machine sounds so accurate.

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fddfgs t1_j946o2e wrote

Yeah, extended fevers lead to brain damage, which severely inhibits your ability to produce offspring.

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Sleepyhowiee t1_j95p0d6 wrote

Given the current state of affairs, I’d argue that brain damage hasn’t seemed to inhibit that much reproduction.

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XTJ7 t1_j96lcug wrote

Well, it's not really brain damage for these people but rather indefinite intellectual hibernation. They could use their brains, they just decided not to.

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Synkope1 t1_j96mssd wrote

They don't, actually. Fevers have to get up pretty high, to 107-108 to cause brain damage, which is pretty darn rare. I can count on one hand the number of fevers I have seen over 107.

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kharmatika t1_j9593fn wrote

Lol I love this for some reason. “We done being on fire yet?” viral load shoots back up “nope.”

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honestdiary t1_j94wzdv wrote

I believe so. Too high of a fever, or too long of a fever, your organs start to cook.

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MrDilbert t1_j96iviq wrote

Side note: that's actually the reason why Ebola is so dangerous: its natural reservoir are bats who have higher body temperature than humans, so when the human body wants to get rid of it, it has to ramp up the fever. And since the virus can handle higher temperatures, the fever has to run hotter and/or longer to kill it off, but has a very high chance of cooking the internal organs as well.

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JustAnotherMiqote t1_j9444mw wrote

Having a fever that lasts longer but doesn't kill you seems like a pretty good evolutionary trait tbh..

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diamondpredator t1_j94sz06 wrote

I thought it wasn't the fever that killed the virus but that the fever made your own immune cells better at defending against it because the higher temperature is a better environment for them.

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JohnnyJordaan t1_j95ej4n wrote

It doesn't outright kill individual pathogens, but it does combine the effects of making it harder for them to survive (so letting the population die out) and increased production and activation of immune cells. But that doesn't mean it's a better environment for them than normal body temperature, as of course the system is designed to handle 99% of the infections in that condition. Fever really is the fallback scenario where all bets are off until they fix the issue, causing all the other effects we call 'being sick'.

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ClownsAteMyBaby t1_j956p6p wrote

Not that I've ever read. It's generally taught that it makes the environent less hospitable to viral/bacterial enzyme function and replication.

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laughingweasel t1_j9661vh wrote

And it really slows down the rate that viruses multiply which allows your immune system to reduce the number of viruses that are able to multiply.

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bonkly68 t1_j991tac wrote

I've heard that white blood cells are about twice as mobile per degree C of temperature rise.

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No_Habit4608 t1_j95gfal wrote

So, based on this, does taking a fever reducer (e.g. acetaminophen or ibuprofen) also reduce the fever, and/or the body’s ability to fight the virus?

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nurseliz21 t1_j95iheg wrote

To a certain extent, yes. You should take an antipyretic if your fever is high (above 39.8°C) and doesn't break. At least these are the recommendations I've always gone by myself. It just prolongs how long the body will fight off the virus. This is the same for cold and flu medicines.

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zhibr t1_j96dfv3 wrote

Right. If the fever would be at its height for the whole time, there would need to be a specific mechanism that stopped it when its not needed anymore. That's much more costly, in evolutionary sense. With a cyclical one, each fever is supposed to die on its own, so it's just a matter of trying again if the previous one didn't work.

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Gamebird8 t1_j96oby3 wrote

And fevers are often just an attempt to mitigate until you can produce an adequate antibody response

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