Avian influenza H5N1: still a pandemic threat?

Highly pathogenic avian influenza H5N1 viruses have become endemic in global poultry populations over the past 25 years and pose an ongoing public health threat. Although the incidence of human cases has declined, viruses from the H5N1 lineage can now be found in poultry throughout Asia, the Middle East and Africa, in addition to causing outbreaks in Europe and the Americas. The recent emergence and spread of reassortant H5Nx viruses, resulting in regional poultry outbreaks, has increased the risk for further evolution of these viruses and possible avian-to-human transmission. Ongoing surveillance and pandemic preparedness for H5N1 and other avian influenza viruses of public health concern are warranted