The avian flu has undergone a critical mutation making it easier for the virus to infect humans, according to a study conducted by researchers at the University of Wisconsin at Madison and published in the journal PLoS Pathogens.
“We have identified a specific change that could make bird flu grow in the upper respiratory tract of humans,” lead researcher Yoshihiro Kawaoka said.
The H5N1 strain of influenza, also known as “bird flu,” has decimated wild and domestic bird populations across the world since it emerged between 1999 and 2002. This highly virulent variety of the flu has been identified as a public health concern because in the past, varieties of influenza have mutated and crossed the species barrier to humans.
Since 2003, 329 humans have been confirmed infected with H5N1, with 201 fatalities. The vast majority of these worked closely with infected birds, such as in the poultry industry.
One of the primary things that keeps bird flu from infecting humans is that the virus has evolved to reproduce most effectively in the bodies of birds, which have an average body temperature of 106 degrees Fahrenheit. Humans, in contrast, have an average body temperature of 98.6 degrees, with temperatures in the nose and throat even lower (91.4 degrees). This vast temperature difference makes it very difficult for the bird flu virus to survive and grow in the human body.
In the current study, researchers found that a strain of H5N1 has developed a mutation that allows it to thrive in these lower temperatures.
“The viruses that are circulating in Africa and Europe are the ones closest to becoming a human virus,” Kawaoka said. But he pointed out that one mutation is not sufficient to turn H5N1 into a major threat to humans.
“Clearly there are more mutations that are needed. We don’t know how many mutations are needed for them to become pandemic strains.”
“We are rolling the dice with modern poultry farming practices,” warned consumer health advocate Mike Adams, author of the book How to Beat the Bird Flu. “By raising chickens in enclosed spaces, treating them with antibiotics, and denying them access to fresh air, clean water and natural sunlight, we are creating optimal conditions for the breeding of highly infectious diseases that can quickly mutate into human pandemics,” Adams said. “Given current poultry farming practices, it is only a matter of time before a highly virulent strain crosses the species barrier.”
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