# 5797
The World Health Organization has posted a brief statement regarding the FAO’s warning earlier this week (see FAO Warns On Bird Flu) of a mutated strain of the H5N1 virus circulating in China and Vietnam.
This FAO announcement has been widely reported by the press, and over the past 48 hours has elicited some criticism (see Australian CMO Calls Bird Flu Warning `Overstated’) for stating that this emerging strain poses `unpredictable risks to human health.”
Given the amount of press coverage this statement has received, the WHO has sought to clarify matters with the following statement.
Evolution of H5N1 avian influenza virus does not increase risk to public health
30 August 2011 -- WHO closely monitors the evolution of influenza viruses and is aware of recent reports of an H5N1 virus (described as H5N1 clade 2.3.2.1) circulating in poultry in parts of Asia. Based on available information, this evolution of the H5N1 virus poses no increased risk to public health. It is not considered unusual because influenza viruses are constantly evolving, especially in areas where they circulate regularly in poultry.
The WHO Global Influenza Surveillance and Response System, the group of experts that studies animal and human influenza viruses that may impact human health, recognized this new clade in February 2011.
WHO also routinely assesses the public health risk from all animal influenza viruses. Based on available information, the identification of this newly-reported H5N1 virus clade does not change the current public health implications of the H5N1 avian influenza viruses for humans. Human cases of H5N1 infection remain rare and sporadic events, occurring mostly in areas where H5N1 viruses circulate regularly in poultry. Human cases could occur wherever the viruses are present in poultry and when humans might be exposed to infected birds or contaminated environments.
As I wrote yesterday, we’ve no indications that this new strain of H5N1 is any more likely to be transmitted to, or among, humans than the earlier strains.
What we are seeing is viral evolution in action. And for influenza viruses, the only constant is change.
For now, this new clade presents the biggest challenge to poultry farmers in countries where it is now endemic. Current vaccines do not protect livestock against it, and so the fear is it will spread further across Asia.
And that could not only result in substantial losses in countries already dealing with low food security, it could potentially expose more people (along with a variety of non-human hosts) to the virus.
Providing the H5N1 virus with more opportunities to evolve and adapt.
Hence the calls for increased surveillance and vigilance.
Not so much for what the public health threat of the H5N1 virus is today, but for what it might become in the future.
