Why do we have fever when we fall sick?
In 1917, doctors proposed an outlandish treatment for syphilis, the incurable bacterial infection that had ravaged Europe for centuries.
Step 1: Infect patients suffering from the later stages of syphilis with the parasite that causes malaria, the deadly bit curable mosquito-borne disease.
Step 2: Hope that material fevers clear the syphilis.
And Step 3: Administer quinine to curb the malaria.
If all went according to plan, that patient would be left-handed alive and free of both diseases. This killed some 15% of patients, but for those who survived, it seemed to work.
It actually became the standard treatment for syphilis until penicillin was widely used decades later. And its driving force was fever.
There’re many mysteries around fever but what do we know is that all mammals, some birds and even a few invertebrate and plant species feel fever’s heat. It has persisted for over 600 million years of evolution. But it has a significant cost. Each 1°C rise raises energy use by 12.5%, equal to about 20 minutes of jogging.
So Why And How Does Your Body Produce a Fever?
Your core temperature is maintained his thermoregulatuon, a set of process that usually keep you around 37 degrees Celcius. These mechanisms are controlled by the brain’s hypothalamus, which detects minute temperature shifts and sends signals throughout the body accordingly.
If you’re too hot, the hypothalamus produces signals that activates your sweat glands or make tour blood vessels dilate, moving blood closer to the skin’s surface–all of which releases heat and cools you off. And if you’re too cold, your blood vessels will constrict and you may start to shiver, which generates heat.
Your body will disrupt its usual temperature equilibrium to induce a fever, which sets in above 38 degrees Celcius. Meanwhile, it has mechanisms in place to prevent it from exceeding 41 degrees Celcius, when organ damage could occur. Immune cells trigger a cascade that tells your hypothalamus to raise body temperature.Your body then gets to work to meet its new “set point” using the mechanisms, it would generate heat when cold. Until it reaches the new temperature, you’ll feel comparatively cool, which is why you might experience chills.
But Why Does Your Body Do That?
Fever mainly triggers a rapid, whole-body immune response. High temperatures cause cells to release heat-shock proteins To deepen your understanding of how your immune system activates during an illness, see how the immune system works in our detailed guide.
ThHeat-shock proteins help lymphocytes reach infection sites fasterFhsp. HSPs help lymphocytes stick to vessel walls and move into infected tissues.
For official guidance on what to do if you’re sick with fever and infection, see the CDC’s advice on precautions when you’re ill.
In the case of viral infections, HSPs help tell nearby cells to dampen their protein production, which limits their ability to replicate. This stunts the virus’s spread because they depend on their host’s replicative machinery to reproduce. It protects nearby cells from viral damage that can cause widespread destruction. HSPs protect cells and help limit a pathogen’s damage.
Diet and nutrition also influence how your body handles infections, for example, learn how a food like milk affects immunity and health.
What Happens Inside Your Body During a Fever?
But for all we know about fever’s role in immune activation, some clinical trials have shown that fever suppressor drugs don’t worsen symptoms or recovery rates. This is why there’s no definitive rule on whether to suppress a fever or let it ride. Doctors decide on a case-by-case basis. Doctors consider fever intensity, immune strength, comfort, and age before treating. And if they allow the fever to run, they advise rest and plenty of fluids.
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