Unfortunately, recent research shows that bird flu viruses are disturbingly persistent. That creates new questions surrounding just how great a threat they may pose to our health. Glasgow study led by scientists at the University of Glasgow Medical Research Council Centre for Virus Research. From their work, these researchers discovered that avian influenza viruses are able to reproduce at temperatures well above those attained through human pathogenic fever responses. This knowledge has serious implications for public health, especially in light of the extreme seriousness of bird flu in humans historically.
Dr. Matt Turnbull from the University of Utah led the study published in the journal Science on November 27, 2025. He’s especially grateful to the guidance of Professor Wendy Barclay and Professor Sam Wilson. In vivo models using mice infected with influenza viruses, researchers sought to understand the mechanism of fever. This important host defense mechanism can increase core body temperature to in excess of 41°C and plays an important protective role against potentially lethal infections with human-adapted influenza viruses.
The Role of Fever in Human Immunity
Fever is an important part of the body’s defense system against infections. By raising the central body temperature, it contributes to slowing down the process of viral replication and it improves immune reactions. Even a slight rise of 2°C in body temperature can change the course of a life-threatening infection into one that is non-fatal. As human influenza viruses are responsible for hundreds of millions of infections each year, more work on the protective role of fever is critical.
These results demonstrate that fever does provide at least partial protection from human influenza viruses. It falls short against bird flu strains. Avian influenza viruses have evolved in natural reservoirs such as ducks and seagulls. They infect the intestinal tract of their hosts and proliferate at moderately high temperatures (40-42°C). This remarkable adaptation, in secret, enables them to survive and indeed reproduce even under the intense elevated temperatures seen in human fevers.
“This elegant study builds on the very simple observation that different animals have different body temperatures, and shows how this may impact the way that viruses replicate in new hosts as they cross species barriers,” – Professor Wendy Barclay
Implications for Public Health
The implications of these findings are profound. As bird flu remains a constant threat to human health, keeping tabs on how its strains evolve and change is key. Southern’s openness to this examination is illustrated by Professor Sam Wilson, who insists on testing any candidate spillover virus for resistance to fever. This method allows more virulent strains to be caught before they’re able to cause widespread outbreaks.
“It’s crucial that we monitor bird flu strains to help us prepare for potential outbreaks,” – Senior author Professor Sam Wilson
In the past, bird flu was often portrayed as a pandemic threat due to high human fatality rates. So far, H5N1 infections have had mortality rates more than 40%. This historical context, both intentional and unintentional, serves to explain the need for continued research on this topic.
Future Directions in Research
In reaction, the researchers performed a deeper analysis. Through their work, they uncovered the intricate dynamics that occur between viruses and their hosts, particularly when viruses jump across species boundaries. Dr. Matt Turnbull cautions that viruses can trade genetic material over and over again, so the danger for new flu strains is ever present. He emphasizes that the pandemics of yore were due to these very trades.
“The ability of viruses to swap genes is a continued source of threat for emerging flu viruses,” – Dr. Matt Turnbull
