In December I wrote about how two different research groups had stitched together new varieties of the deadly H5N1 Bird Flu that were easily transmissible between ferrets through droplets in the air. Many were worried that if their results were published, terrorists could use the data to create a devastating biological weapon. As a result, publication of both papers was put on hold. However, the paper by Yoshihiro Kawaoka and colleagues at the University of Wisconsin, Madison and Tokyo, is now set to be published in Nature (see “One H5N1 Paper Finally Goes to Press,” in Science, May 4, 2012). The second paper, by Ron Fouchier and colleagues at Erasmus MC, Rotterdam, Netherlands, has been delayed by bureaucratic red tape, but is slated to be published by Science.
Wild avian influenza strains are currently not easily transmissible from person to person and are overwhelmingly contracted only through direct contact with infected birds. Yet for those who do contract the virus, the mortality rate has been terrifyingly high (around 60%). Virologists have been predicting for years that this or another highly pathogenic avian influenza (HPAI) strain could mutate and develop person-to-person transmissibility (like seasonal flus), leading to a deadly pandemic like the one in 1918, which killed between 50 and 100 million people worldwide.
Scientists argue that research like that conducted by the Fouchier and Kawaoka teams is essential for understanding how influenza viruses mutate and develop phenotypes that are dangerous to humans. This information would be helpful in terms of assessing pandemic risks and in terms of veterinary monitoring. For example, birds that are discovered carrying viruses with the necessary mutations could be immediately culled and monitoring increased in areas where they are discovered.
Kawaoka et al discovered that four mutations on the Hemaglutanin (the “H” in H5N1) protein would allow respiratory transmission of the virus in ferrets, which are one of the closest animals models to humans. Most influenza strains that are easily transmissible between ferrets are also easily transmissible between people. The same is not always true for bird strains.
While these new strains can spread easily through the air between ferrets, they were far less deadly than wild H5N1 and even though ferrets tend to be a good approximation for the effect in humans, scientists do not know if these new strains will in fact spread between people. Furthermore, it is not trivial to make virulent strains of influenza. The equipment, facilities and expertise necessary to produce virulent new strains of influenza are not easy to come by and it is unlikely that any terrorists would have the skill and access to the necessary materials.
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