For centuries, the question of fever – friend or foe – has been debated, but new research is shedding light on its role in fighting off viruses.
From ancient Greece, where Hippocrates believed fever could 'cook out' illness, to the 18th century, when it was seen as a dangerous ailment, the understanding of fever has evolved dramatically. Today, we know that fever is a crucial part of the immune system's response to pathogens, shared across many animal species. But how exactly does it work?
"There's a cultural knowledge that there's this relationship between temperature and viruses, but at a molecular level, we're quite unsure how temperature might be impacting viruses," says Sam Wilson, a microbiologist at the University of Cambridge. There are two main theories: either the heat itself directly harms the virus, or it's a way to boost the immune system, or perhaps a regrettable but unavoidable byproduct of fighting off an infection.
Wilson's curiosity led him to a fascinating study published in Science, which suggests that elevated temperature alone can be enough to combat certain viruses, at least in mice.
But here's where it gets controversial...
To isolate the effects of fever from the overall immune response, Wilson and his team used bird flu, because birds naturally run hotter than humans. They pinpointed a part of the bird flu genome, called PB1, that helps the virus thrive in warm environments. They then inserted this heat-tolerant snippet into a human flu virus, creating two nearly identical influenza strains: one normal, and one heat-tolerant.
They tested these strains on laboratory mice, which don't typically develop fevers during influenza infections. By housing some mice at slightly elevated temperatures, they simulated a fever. The results were striking: mice infected with the heat-resistant strain still got sick, but those exposed to the normal strain seemed relatively unaffected by the heat, suggesting the heat itself helped fight off the flu.
"This study reinforces the idea that temperature alone is an important and effective," part of the body's attempt to respond to infection, says Daniel Barreda, a microbiologist at the University of Alberta. However, he notes that this doesn't rule out the possibility that fever also boosts the immune system, which could be critical for viruses less sensitive to temperature.
And this is the part most people miss...
Joe Alcock, an emergency physician and researcher at the University of New Mexico, praises the study but cautions against assuming fevers work the same way in humans as they do in mice. He raises an important question: "Is it possible that by taking Tylenol or ibuprofen for a viral infection, that I might be actually making it tougher for my body to get rid of the infection?" This is a question that remains unanswered.
What do you think? Do you agree with the study's implications? Do you think we are too quick to treat fevers? Share your thoughts in the comments below!
