Whilst we are all more focussed on swine flu these days, the threat of avian influenza or “bird flu” is still present. New research from Imperial College and the University of North Carolina suggests we may not have to worry however, because our noses are just too cold.
It sounds strange, but the 32° Celsius of the human nose is not a high enough temperature for avian influenza viruses to survive, according to the study published in PLoS Pathogens. The viruses normally infect the guts of birds, typically a warmer 40° Celsius, so the researchers suspect that our lower temperature protects us. The avian influenza viruses normally enter the human body through the nose, so are unlikely to infect people and cause illness.
There is also the possibility that a human influenza virus could mutate by adapting proteins from an avian influenza virus. The study shows that a virus of this form would also struggle to take hold at 32° Celsius, just like the regular avian influenza virus, so we would be safe unless the virus mutated further.
Thankfully, no one had to catch the flu to conduct this research. Cells from the human airway were grown in the lab and then infected with a selection of human and avian viruses. Whilst the human varieties thrived at both 37° Celsius, our core body temperature, and at 32° Celsius, the avian viruses could only grow well at 37° Celsius.
Professor Wendy Barclay, one of the authors of the study from the Division of Investigative Science at Imperial College said:
“It would be impossible to develop vaccines against all 16 subtypes of avian flu, so we need to prioritise. By studying a range of different viruses in systems like this one we can look for warnings that they are already beginning to make the kinds of genetic changes in nature that mean they could be poised to jump into humans; animal viruses that spread well at low temperatures in these cultures could be more likely to cause the next pandemic than those which are restricted.”