The common wisdom is a fever helps our body fight off infections. But how?
If higher body temps kill some infections then why haven’t they evolved to be resistant to those higher body temps? Extremophile bacteria exist so it is not outside the bounds of reality that some toxic to us could manage to survive 10 degrees higher than human body temperature.
Given that a fever is also (at extremes) dangerous to the person who has a fever is it really a biological benefit?
The common wisdom was that microbes evolved to live and reproduce at certain temperatures within our bodies. If you raise that temperature enough the bacteria or virus was less likely to survive, giving your immune system a better chance of fighting it. I doubt it’s as simple as that, but that’s what I was taught in college 30 years ago.
Many of our bodily processes are chemical in nature. As a rule, chemical processes work faster at higher temperatures (we put many foods in the refrigerator or freezer to slow down decay). So that is a major element as well.
Fever and the thermal regulation of immunity
“Fever is a cardinal response to infection that has been conserved in warm and cold-blooded vertebrates for over 600 million years of evolution. The fever response is executed by integrated physiological and neuronal circuitry and confers a survival benefit during infection. Here, we review our current understanding of how the inflammatory cues delivered by the thermal element of fever stimulate innate and adaptive immune responses. We further highlight the unexpected multiplicity of roles of the pyrogenic cytokine interleukin-6 (IL-6), both during fever induction as well as during the mobilization of lymphocytes to the lymphoid organs that are the staging ground for immune defence. Finally, we discuss the emerging evidence that suggests the adrenergic signalling pathways associated with thermogenesis shape immune cell function.”
The article explains nicely how it seems to benefit us.