Study Warns That Bird Flu Viruses Can Withstand Fever, Heightening Risk To Humans

A recent study by researchers from the Universities of Cambridge and Glasgow has found that bird flu viruses can replicate even at temperatures associated with fever, challenging one of the body’s most effective natural defence mechanisms.

The findings raise concern over the potential threat avian influenza continues to pose to humans.

Human flu viruses, categorised as influenza A, are typically sensitive to increased body temperature. Even a slight rise of 2°C is usually enough to significantly weaken the virus, turning severe infections into manageable illnesses. However, the new research suggests that this protective mechanism may not work against avian influenza strains.

While human flu viruses struggle to survive elevated temperatures, avian influenza viruses appear to be adapted to thrive in warmer environments. In their natural hosts, such as ducks and seagulls, these viruses often infect the gut, an environment where temperatures can reach between 40°C and 42°C.

This adaptation means that when bird flu infects humans, fever may not be enough to halt viral replication. Professor Sam Wilson from the Cambridge Institute of Therapeutic Immunology and Infectious Disease noted that although human bird flu infections remain relatively rare, the historically high fatality rates, including more than 40 per cent mortality in earlier H5N1 outbreaks, remain a cause for concern.

Key Viral Gene Helps Avian Strains Resist Fever

Published in the journal Science, the study used mouse models to understand how body temperature influences viral behaviour. Since mice do not naturally develop fever in response to influenza A, scientists replicated fever-like conditions by increasing the ambient temperature of their environment.

Researchers discovered that the PB1 gene, involved in viral genome replication, plays a crucial role in determining a virus’s temperature sensitivity.

Viruses carrying an avian-like PB1 gene were capable of withstanding fever-level temperatures and went on to cause severe illness in the mice.

The findings underline the importance of understanding what allows some avian influenza viruses to cause severe disease in humans.

As concerns persist over the pandemic potential of strains such as H5N1, researchers emphasise that improving surveillance and preparedness strategies is essential to mitigate future risks.

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