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  • 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 but curable mosquito-borne disease.

  • Step 2: Hope that malarial fevers clear the syphilis.

  • And step 3: Administer quinine to curb the malaria.

  • If all went according to plan,

  • their patient would be left 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 are many mysteries around fever,

  • but what we do 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.

  • For every 1 degree Celsius of temperature increase in the human body,

  • there's a 12.5 percent increase in energy required,

  • the equivalent of about 20 minutes of jogging for some.

  • So, why and how does your body produce a fever?

  • Your core temperature is maintained via thermoregulation,

  • a set of processes that usually keep you around 37 degrees Celsius.

  • 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 activate your sweat glands or make your 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 Celsius.

  • Meanwhile, it has mechanisms in place to prevent it

  • from exceeding 41 degrees Celsius, when organ damage could occur.

  • Immune cells that are fighting an infection can induce a fever

  • by triggering a biochemical cascade that ultimately instructs

  • your hypothalamus to increase your baseline temperature.

  • Your body then gets to work to meet its newset pointusing the mechanisms

  • it would to generate heat when cold.

  • Until it reaches this new temperature, you'll feel comparatively cool,

  • which is why you might experience chills.

  • But why does your body do this?

  • While the jury's still out on how higher temperatures directly affect pathogens,

  • it seems that fever's main effect

  • is in rapidly inducing a whole-body immune response.

  • Upon exposure to raised internal temperatures,

  • some of your cells release heat shock proteins, or HSPs,

  • a family of molecules produced in response to stressful conditions.

  • These proteins aid lymphocytes, one of several kinds of white blood cells

  • that fight pathogens, to travel more rapidly to infection sites.

  • HSPs do this by enhancing thestickinessof lymphocytes,

  • enabling them to adhere to and squeeze through blood vessel walls

  • so they can reach the areas where infection is raging.

  • 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 also protects surrounding cells from damage since some viruses spread

  • by rupturing their host cells, which can lead to large-scale destruction,

  • the build-up of detritus, and potentially even organ damage.

  • The ability of HSPs to protect host cells and enhance immune activity

  • can limit the pathogen's path of destruction inside of the body.

  • 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.

  • The fever's duration and intensity, as well as their patient's immune status,

  • comfort level, and age will all play a role in their choice of treatments.

  • And if they do let a fever ride,

  • they'll likely prescribe rest and plenty of fluids to prevent dehydration

  • while the body wages its heated battle.

In 1917, doctors proposed an outlandish treatment for syphilis,

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B2 fever syphilis body temperature immune hypothalamus

Why do you get a fever when you're sick? - Christian Moro

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    林宜悉 posted on 2020/11/12
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