Since the beginning of December 2016, nearly 400 households ofinfluenza highly pathogenic avian disease (HPAI) H5N8 and H5Nx appeared in French farms, in particular in the south-west zone, one year after the start of the epizootic ofinfluenza then due to other highly pathogenic H5N1, H5N2 and H5N9 viruses. Many European countries are affected, either by cases found in wild birds, or by outbreaks in domestic poultry (at the beginning of March, 27 European countries had made a declaration to the World Organization for Animal Health (OIE) on the presence of foci). Currently, waterfowl farms are the most frequently affected.
This new virusnot transmissible to humans, very probably introduced into France by wild birds, is particularly pathogenic for poultry farms, including waterfowl, in which it spreads rapidly. The health situation is evolving differently depending on the areas considered: while some of the regulated areas established to control the spread of the virus around the detected outbreaks are stabilizing (particularly in the departments of Tarn, Aveyron and Deux-Sèvres), an area concentrating the majority of the latest confirmed outbreaks, including part of the departments of Gers, Landes, Hautes-Pyrénées and Pyrénées Atlantiques, as well as in Lot-et-Garonne, has not yet stabilized.
High risk vis-à-vis theinfluenza poultry in France: risk assessment mobilized
In this context, as soon as the first cases appeared in countries neighboring France, the DGAL urgently requested ANSES’s opinion on the circulation of HPAI viruses of the H5N8 subtype detected in Europe. The “IAHP” expert group, which has been working on this theme since the first outbreaks of the previous episode, which occurred at the end of 2015, was mobilized urgently. On the basis of its report, the Agency issued its opinion on November 17, considering that the probability of introduction of infected wild birds, in a homogeneous way in all the wetlands of metropolitan France, including Corsica, is ” very high” and that the probability of an outbreak of HPAI H5N8 in wild birds in these areas is “high”.
These conclusions have led the Ministry of Agriculture, Food and Forestry (MAAF) to decide to raise the level of risk vis-à-vis the disease from “negligible” to “high” in the areas with particular risk corresponding to wetlands, and “moderate” in the rest of the national territory.
In view of the rapid development of the HPAI H5N8 situation on French territory and the appearance of cases in wildlife in Nord-Pas-de-Calais (calling ducks) and outbreaks in farms in Tarn (palmipeds), ANSES again received an emergency request at the beginning of December 2016. The conclusions of its opinion led to the publication of the ministerial decree of 5 December 2016, which puts the whole of metropolitan territory at risk ” high” vis-à-vis theinfluenza avian.
The proliferation of outbreaks in waterfowl farms and to a lesser extent other species of domestic birds in the protection and surveillance zones of Gers, Landes and northern Hautes-Pyrénées and Pyrénées-Atlantiques has led to MAAF to adopt a new strategy. Since January 5, 2017, in order to stop the spread of this new virus as quickly as possible, the slaughter of waterfowl bred outdoors in the above-mentioned area has been underway. Faced with the multiplication of cases in domestic waterfowl, the slaughter area was extended at the end of February, in order to ensure accelerated control of the infection and possible repopulation of farms after a long period of crawl space.
At the request of the MAAF, the group of HPAI experts is continuing its work, aiming to define a methodological approach allowing it to be able to proceed, with the best possible reactivity, to the adjustment of the risk levels, and this whatever the circulating HPAI viruses and the epidemiological context.
The Ploufragan – Plouzané Laboratory and the ESA Platform involved
ANSES’s Ploufragan-Plouzané Laboratory, national reference laboratory (NRL) forinfluenza avian, was strongly mobilized by the emergence of this new virus. Since the beginning of this crisis in November 2016, the NRL has been mobilized seven days a week to sequence the genes of the H5N8 virus in several hundred samples, in order to confirm the highly pathogenic nature of the viruses highlighted by the laboratories of veterinary analyses, for which the NRL also provides the reagents necessary for first-line diagnosis.
The Ploufragan-Plouzané Laboratory was also able to sequence the complete genome of two viruses from samples from the first outbreak in Pas-de-Calais (calling ducks) and the first case identified in domestic birds in the Tarn, then that of another hearth identified in the Deux-Sèvres in a barnyard. The genomic sequence of the first virus is similar to that of viruses detected in northern Europe, while that of the second virus is similar to that of a virus initially detected in Croatia. These first results suggest that HPAI H5N8 was introduced into France by two different routes, probably by migrating birds. The sequence of the virus isolated in Deux-Sèvres is also similar to that of the viruses detected in northern Europe, thus demonstrating that this focus is independent of those identified in the South-West of France.
The NRL also conducts research aimed at clarifying the genetic evolution of viruses, as well as the pathogenicity of newly detected viruses. In the absence of available data on the dissemination of the virus and its persistence in the environment, information which is nevertheless crucial for the risk manager, the Ploufragan-Plouzané Laboratory is also conducting research on the persistence of the virus in manure from ducks and the development of a method for its detection in farms and their environment. The latter would make it possible to detect the most contaminated areas and materials and to assess the effectiveness of the cleaning and disinfection measures implemented, prior to the resumption of activity and the reintroduction of animals on the sites. Epidemiological investigations are also conducted in the field in the various departments concerned by the Ploufragan Avian Epidemiology team (EBEAC) alongside the departmental directorates in charge of population protection (DDecPP). These epidemiological investigations are coupled with the work of virologists and epidemiological investigations carried out in the outbreaks detected by the DDecPPs of the departments concerned.
The analysis of epidemiological links should make it possible to better understand how the virus was able to be introduced and then spread between farms and contribute to defining and evaluating the possible measures to better control these epizootics ofinfluenza avian, on which the Laboratory’s virologist and epidemiologist experts are regularly questioned by the public authorities.
The ESA Platform, whose role is to provide precise and reliable information and analyzes on the epidemiological situation of the diseases present in France and their evolution, has also been heavily involved in monitoring the evolution ofinfluenza avian and the circulation of the H5N8 virus. Situation updates are carried out on a weekly basis both for France, on the basis of the results transmitted by the LNR and the Directorate General for Food, and for the European continent through its International Health Watch system. These status updates published in the ESA Platform Resource Center are widely consulted (the number of monthly connections to the site quadrupled between October and December, rising from 5,000 to 20,000 monthly connections). The ratings of the ESA Platform are now taken up by generalist media (eg Le Monde, TV5 Monde) as well as by monitoring platforms (eg Promed). ANSES also contributed to setting up an information system for MAAF’s decentralized services (DDcePP and regional food services), updated daily and making it possible to monitor the evolution of outbreaks and areas. of restrictions.