Avian Influenza: Insights for the southern hemisphere

Dr David E. Swayne, Laboratory Director at the Southeast Poultry Research Laboratory at the US National Poultry Research Center Agricultural Research Service, USDA, tells us what makes this virus different and offers his advice for the poultry sector in the southern hemisphere ahead of winter.

How serious is this outbreak compared to previous avian influenza outbreaks?

The current outbreak strains in Europe and Asia are the H5Nx HPAI viruses that have a genetic origin from the initially identified H5N1 High Pathogenicity Avian Influenza Virus (HPAIV) from the Guangdong province in China in 1996. This virus lineage has spread to many additional countries and changed by drift and shift. There have been changes in hemagglutinin (HA) protein by mutations in the gene that have produced diverse HA structure which have necessitated change in vaccine seed strains and have also resulted in changes in the biology of the virus infections in poultry and wild birds. These newest viruses are still highly lethal to poultry but vary in ability to infect and cause severe disease and death in wild birds.

What makes this outbreak different to the previous one?

This clade of virus has infected migratory waterfowl and spread across multiple countries in Europe and Asia with overflow into domestic poultry causing outbreaks in backyard and commercial poultry. This is similar to the outbreaks seen in the USA in 2014-2015. But many previous outbreaks with 1996 lineage of HPAIV do not always spread by migratory birds.

What advice do you have for the southern hemisphere as they prepare for winter?

Increased surveillance in migratory birds and outdoor poultry for early HPAIV detection and the development of mitigation strategies to reduce introduction into commercial poultry to limit onward spread.