The fever response may be more related to activating the immune system and helping circulate anti-microbial proteins through the body than actually damaging the microbes through temperature alone. Also, viruses are more prone to thermal degradation than bacteria, so a small change in temperature may cause the virus to lose structural stability.

I am not sure though the possibility is that some type of proteins may be structurally modified that can cause growth arrest or killing or microbes.

On the other hand the increased temperature may also activate the phagocytic and microbial killing activity of macrophages and neutrophils.

Some new type of antimicrobial products may be generated/activated at elevated temperature.

Although may be not obvious in in vitro conditions, the enhanced temperature can still slow down the growth of microbes.

The fever response may be more related to activating the immune system and helping circulate anti-microbial proteins through the body than actually damaging the microbes through temperature alone. Also, viruses are more prone to thermal degradation than bacteria, so a small change in temperature may cause the virus to lose structural stability.

I agree whit Jay

It is exceedingly unlikely that a 3 degree increase in temperature would directly affect pathogens. (Pathogens need to tolerate massif thermal ranges, so I don’t suspect that a febrile response is a potent pathogen killer.)

During an infection, there is a spectacular increase in cell proliferation in the bone marrow (to expand the immune cell population). Because the synthesis of proteins and nucleotide are literally the two most ATP-demanding activates in proliferating cells, it is likely that the proliferation necessitate more effective ATP production. In this regard, it is worth noting that the mitochondria actually perform slightly better at elevated (i.e. febrile) temperatures:

“The increase of temperature in the febrile range (40°C) slightly activated mitochondrial function through stimulation of the respiratory module, without affecting the kinetics of the proton leak and phosphorylation modules.”

(https://www.tandfonline.com/doi/full/10.3109/02656730903262140)

Also, chemical reactions in general happens faster at elevated temperatures. So, it is likely that febrile temperature also helps speed up anabolic reactions, thereby facilitating the consolidation of biomass into immune effector cells.

In summary, one key reason for the febrile response is to mobilise the immune system during an infection.

I agree with Gustav van Niekerk