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Why are we afraid of fevers? Treating fever with medicine also affects the immune system

January 12, 2021 3:15:09 PM IS

Among the many measures my local Y is using to prevent the spread of Covid-19, instantaneous temperatures are taken with a head-on scanner before people can enter the building. Curious about how “hot” it was on a cold and rainy day, I asked the assistant what he was recording: 96.2. The last time they checked my temperature in a medical center, it was 97.5ºC. What happened to the 98.6 degrees Fahrenheit that I and most doctors long consider to be normal body temperature?

As if reading my mind, Dr. Philippa Gordon, a pediatrician from Brooklyn, sent me an article, “People’s bodies are now colder than ‘normal’, even in the Bolivian Amazon By two anthropologists, Michael Gurven and Thomas Kraft of the University of California at Santa Barbara.

Like them to writing inside The conversation, “There is no one“ normal ”body temperature that is unique to everyone at all times. On the contrary, body temperature varies, not only from person to person, but also throughout the day: lower in the morning, higher at night; get up during and after exercise; varying at different times of the menstrual cycle and at different ages, lower for the elderly like me.

Additionally, researchers who took hundreds of thousands of temperature readings from people in Palo Alto, California, found that 97.5 was the new standard, or roughly one degree from what the German physician, Dr. Carl Wunderlich, had set for himself. in 1867 in a study involving 25,000 people. (Wunderlich’s research found that ‘normal’ body temperature ranged from 97.2 to 99.5).

Looking at data from 1862 to 2017, Dr. Julie Parsonnet, a professor of medicine at Stanford University School of Medicine, and her co-authors found a steady drop in average body temperature of about 0.05 degrees Fahrenheit per decade. . He observed that at least 75% of normal temperatures are now below 98.6ºC.

If my body temperature was 98.6, would that mean I have a fever? Maybe, said Sharon S. Evans, professor of oncology and immunology at Roswell Park Comprehensive Cancer Center in Buffalo, New York, though 100.4 is generally considered the lower end of the febrile spectrum.

In a review written with two colleagues, Elizabeth A. Repasky and Daniel T. Fisher, Evans showed that fever is beneficial in most circumstances, reduces the severity of the illness, and shortens its duration. (However, he stressed that patients should follow their doctor’s advice on taking fever-reducing medications.)

“Fever acts to mobilize multiple arms of the immune system, a very well-conserved function in many species, both warm-blooded and cold-blooded,” he explained in an interview. “Fever affects all aspects of the immune system to make it work better.”

The temperature scan gun is used to check body temperature as a Covid-19 detection measure. Image: Unsplash

For starters, Evans said, fever activates innate immunity – the mobilization of white blood cells – neutrophils that patrol the body for pathogens and macrophages that engulf them. Macrophages, in turn, send an alarm that help is needed, causing adaptive immunity (T cells and B cells) to kick in. These cells initiate a specific response to the invader: the production of antibodies a few days later.

“Treating a fever can prolong or worsen the disease,” said Dr. Paul Offit, a vaccine specialist at the University of Pennsylvania, in “Hippocrates was right: treating a fever is a bad idea,” a fascinating YouTube presentation. from the Philadelphia College of Physicians.

“Fever improves survival,” Offit reported. This explains its persistence throughout animal evolution, even if it carries a significant metabolic cost. Immunity, both innate and adaptive, “works better at higher temperatures,” he said.

So when you take medications like acetaminophen (Tylenol and its generic forms) or ibuprofen to suppress fever, you are actually working against nature’s inherent protective benefits. Yes, a fever reducer would probably help you feel better, alleviating symptoms like headaches, muscle aches, and fatigue. But, Offit emphasized, “you’re not supposed to feel better. You are supposed to stay under the covers, stay warm and escape the infection ”, not go out and infect others.

“We have a fever for a reason,” he says. Fever helps reduce viral shedding and shortens the duration of illnesses like the flu.

Grandma’s proverbial cold remedy, hot chicken soup, probably helps because the steam raises the temperature of the nasal passages, suppressing the reproduction of the virus, he suggested.

Evans and his colleagues wrote: “The fact that fever has persisted throughout vertebrate evolution strongly supports that feverish temperatures confer a survival advantage.” This is also true for invertebrates like insects. And when cold-blooded animals like lizards or bees get sick, they try to raise their body temperature by increasing their physical activity or seeking a warmer environment, Evans said.

So why are we so determined to suppress the fever? Fear is one reason, said Gordon, the Brooklyn pediatrician, who said desperate parents often call in the middle of the night when a child’s fever rises. She suggested that doctors warn parents in advance to expect the child’s fever to rise at night and explain that high fevers caused by infection are not harmful.

“The body has a built-in thermostat, the hypothalamus, that keeps temperatures from getting high enough to cause harm,” he said, and febrile seizures – brief seizures, tremors, and possibly loss of consciousness that affect some young children – are the result. how temperatures rise rapidly, not how high they get. In a genetically sensitive child, a seizure can occur when the temperature rises rapidly, even at low temperatures, for example 99 to 100.8ºC.

“Febrile fits are terrifying and frightening for parents to watch, but they don’t cause any harm,” Gordon said. However, he added that fever is a concern in very young babies who have immature immune systems and who have not yet been vaccinated against serious diseases.

Even knowing the benefits of fever to fight infection, Gordon said he would still recommend fever-reducing medications if a child, especially a non-verbal child, is feeling very miserable and may not be able to sleep or sleep. eat.

Generally, adults are advised to see a doctor if the fever exceeds 103 degrees.

An important warning regarding high fevers: Unlike fevers that result from infection, there is no natural limit to environmentally induced fevers, as there might be if a child is locked in a car. It is hot or if an overdressed athlete exercises on a hot day, which can lead to fatal heatstroke.

Consumers should also think about how the temperature is taken before interpreting the results. The ear temperature is usually slightly higher than the oral temperature, which in turn is higher than the armpit temperature or the forehead scan.

To ensure a reliable reading, a newborn’s temperature should be taken with a rectal thermometer, Gordon said. But for older kids who have a fever, the exact number of degrees doesn’t really matter unless they’re not vaccinated, he said.

Jane E. Brody. vs. 2021 The New York Times Company