November 2025 - Magazine - Page 131
November 2025
ing of fever came after germ theory arrived, says Frampton, when we learned more about
infections and fever started being seen as a symptom rather than a disease itself.
Germ theory
Germ theory, first published by Louis Pasteur in 1861, identified microorganisms invading our
bodies as the cause of disease. The French scientist paved the way towards our understanding of microbial infections as something we can prevent through cleanliness.
After a surge in maternity deaths during childbirth due to "childbed fever" (now known as
postpartum infection) in a Parisian hospital back in 1875, Pasteur proposed that the infection was being spread by physicians and hospital attendants. He promptly told clinicians to
wash their hands and sterilise their tools with heat.
We now know fever is part of our bodies' innate response to infection. Found across the animal world in both warm-blooded and cold-blooded vertebrates, the chills when fever settles in, followed by the sticky and relentless sweats when it breaks, is our body's intruder
alarm 3 and attack 3 system.
Fevers signal that pathogens and other hostile actors are making our bodies their home 3
and that we're putting up a fight. Unpleasant as they may be, they help us to get rid of
these intruders. When unchecked, though, fevers can become harmful.
What is a fever?
A fever is generally characterised by a body temperature above 38C (100F). It can occur
as our body's response to infections, but it can also be triggered by auto-immune diseases,
inflammatory diseases or after a vaccination.
As our bodies react to the threat of a virus or pathogenic microorganism, such as fungal or
bacterial infections, our core temperature rises. This is an important mechanism in our immune response as it makes our bodies less cosy for those harmful pathogens 3 they struggle
to replicate or thrive inside us at these higher temperatures.
"The body senses something strange, like a virus or bacteria. The thermostat is twisted a little
bit to increase the temperature to the level that the response to this danger can be more
efficient," says Mauro Perretti, a professor of immunopharmacology and inflammation expert at Queen Mary University of London in the UK. "Cells will work better; enzymes will work
better. It's a reset, which is going to be transient, of course."
In our bodies, there are tiny windows between too cold, just right and too hot. When our
core temperature drops below 35C (95F, known as hypothermia) shivers, slurred speech
and slow breathing are triggered. At the opposite end of the scale, a rise in core body temperature above the normal range for a prolonged period (hyperthermia) can be dangerous and harmful to our internal systems, including the central nervous system, especially
