Publication: Role of Backyard Flocks in Transmission Dynamics of Highly Pathogenic Avian Influenza
The results of the study were presented to the SPACE in September 2018 on the occasion of the AMVA avian pathology morning.
Health risks related to backyards
Family or backyard breeding farms has been constantly developing for several years in France, and the demands for health support for these “breeding farms” have become very significant. International research has shown that backyards can be a challenge for the control of major health danger (avian influenza, of course, but also Newcastle disease, salmonella, mycoplasma, etc.).
The application of the notion of “biosecurity” is a problem for these small and amateur farms. However, it is likely that the practices of these farms make them particularly vulnerable to certain pathogens. Health monitoring of these farms is also complicated because of the difficulty in identifying them. The assessment of the circulation of pathogens in this farming category will also make it possible to shed light on the analysis of the health risks associated with poultry farming in France.
A specific study on the contribution of backyard poultry to the spread of influenza viruses during the 2016-2017 episode
The Avian Biosecurity Chair of the National Veterinary School of Toulouse carried out a study of the health status of backyards located within a radius of 1km around H5N8 (HP) outbreaks in 39 municipalities in the Gers county (Figure 1). 169 backyards were identified and 70 of them were surveyed and sampled from March to May 2017. Serological and virological status have been determined. Descriptive statistics were then compiled to estimate seroprevalence, define practices and identify risk factors.
Results of the study
Backyard seroprevalence has been estimated at 25% for avian influenza and 11% for subtype H5. It has been shown that if all avian influenza viruses are considered together, backyards with palmipeds are twice as likely to be HIV positive. Similarly, for all subtype H5 viruses, a backyard with palmipeds was 5 times more likely to have an HIV-positive status. Above all, the existence of a link between backyard poultry and commercial farms is a very significant risk: this risk of HIV infection has been assessed as 6 times higher for avian influenza and 20 times higher for subtype H5.
These results indicate that while backyards appear to have played a very limited role in the spread of HPAI H5N8 viruses between commercial poultry farms during the 2016-2017 outbreak, the presence of palmipeds and, most importantly, “human links” with the commercial poultry sector appear to be key risk factors. This work is continuing within the framework of the University of Marie Souvestre thesis project, in order to better assess the health risk and propose targeted biosecurity measures, based on a detailed knowledge of the agents present in the backyard and the links with commercial livestock farms.
