What is an automatic increase in body temp above the normal which occurs to destroy the bacteria and the viruses that make a person sick?

Answer 1

The hypothalamus regulate body temperature. Pyrogens are a main component in elevating body temperature. These can be induced either by the body in response to inflammation, and/or by bacteria or viral particles. Pyrogens then in turn increase the production of interleukin by immune cells. The interleukin1 hormone then increases the production of prostaglandin in the hypothalamus. The hypothalamus senses the rise if prostaglandin and increases the basal body temperature, thus increasing temperature. If there is enough stimulation (high viral or high bacterial load), then the temperature will rise enough to the medical classification of a fever. Fever is hypothesized to inhibit, or slow down, the metabolism of bacteria. Bacteria can only operate at certain designated mediums, or environments; one area which includes temperature. This is due to the kinetics or molecular characteristics of enzymes and proteins that enable the bacteria to live. The kinectics have evolved a specific temperature niche, and any deviation of the preferred temperature alters the amount of activity (kinetics) of the enzymes/proteins, thereby slowing growth, activity, and potentially killing the bacteria. Furthermore, increased temperature raises the kinetics of the body's defenses and can aid in establishing a faster line of defense, by modulating immune factors and eliciting an immune response capable of containing an infection. Viral infections work similarly, however, are thought to have less responsiveness/effect to a rise in temperature, and thus, may be a reason why viral illness causes less severity in febrile illness as compared to bacterial illness. Furthermore, bacteria are known to cause more pyrogens, and likely the immune system evolved more in favor of containing bacterial infections given the higher mortality rate in untreated/pre-antibiotic era of bacterial infections rather than the self-resolving viral illness.