Risk assessment of transmission of highly pathogenic avian influenza H5 viruses into French broiler and layer farms from other poultry sectors.
TL;DR
The role of some pathways, especially management of manure and dead birds in the probability of introduction into broiler or layer farms is highlighted, especially management of manure and dead birds in the probability of introduction into broiler or layer farms.
Abstract
Highly pathogenic avian influenza (HPAI) H5 viruses are a major threat to the French poultry sector. All sectors are affected and virus transmission between sectors has been reported. The objective of this work was to identify the risk of virus transmission to the broiler and layer sectors from any other poultry sector in France through nine indirect transmission pathways. We used scenario tree modelling of data collected from the literature or expert knowledge. Three questionnaires were produced, one for each field of expertise: avian influenza, the broiler and layer sectors. The experts' estimates were combined using a beta distribution weighted by their confidence level. Monte Carlo iteration was used to combine the different probabilities of the scenario tree and to assess the risk of transmission. In the broiler sector, the probability of viral transmission was the highest when indoor broiler farms were exposed farms and duck farms were source farms and high when turkey and guinea fowl farms were source farms. In the layer sector, probabilities of transmission were similar between all types of farms as source farms and layer farms as exposed farms. Probabilities were very low between breeder farms but similar in all the sectors. This work highlights the role of some pathways, especially management of manure and dead birds in the probability of introduction into broiler or layer farms. These results can be used to improve management of the risk of HPAI H5 transfer between different poultry sectors in France.