The threat of highly pathogenic avian influenza (HPAI) outbreaks in poultry remains high, with several poultry farms becoming infected in recent years. In order to gain more insight into the course and transmission of HPAI infections, Wageningen Bioveterinary Research (WBVR) has examined the disease symptoms, virus shedding, and mortality following infection with recent H5 viruses.

The research shows that an infection with the HPAI H5N8-2014, H5N8-2016, or H5N6-2017 virus differs considerably between chickens, ducks and Eurasian pigeons. The pathogenicity of the viruses for chickens is higher than that for ducks and Eurasian pigeons. The results also suggest that the pathogenicity of HPAI H5 viruses and the virus shedding for ducks is evolving, which may have consequences for the risk of introduction of these viruses into the poultry sector.

Avian influenza virus easily transmissible via water

The research also observed higher levels of virus shedding for ducks and pigeons infected with the 2016 and 2017 viruses than for the 2014 virus. Infected wild birds (such as pigeons) can introduce the virus to poultry farms through bird faeces.

The more of the virus present in bird faeces, the easier it is to transmit the virus to poultry.

This research also shows that the virus can survive for a long time in water (more than a week) and that chickens can easily become infected by drinking water contaminated with bird faeces.
 
WBVR is conducting further research into the genetic factors and other aspects that determine the pathogenicity of HPAI viruses. A better understanding of the characteristics of HPAI viruses can contribute to the prevention of future outbreaks.

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