It’s a bit like the Covid-19 epidemic on a bird scale. A very important episode of avian flu affects Europe and in particular the South-West of France. The State thus plans to slaughter more than a million poultry in the region as a preventive measure to put a stop to the rapid progression of the H5N8 virus – also called Avian Influenza or avian flu.
So that the virus no longer finds a medium on which to multiply, there should no longer be any ducks, hens or turkeys on farms in an area comprising 226 municipalities, mainly in the south of the Landes, but also in the west of Gers and northern Pyrénées-Atlantiques. This involves “potentially” slaughtering 1.3 million animals, especially ducks, the ministry said, and would bring the total of animals slaughtered since the start of the epizootic at the end of November to 2.5 million.
However, solutions and objectives were put in place after the last major episode of avian flu precisely to avoid the elimination of infected animals. But the strain of H5N8 that circulates today in Landes farms has a particularity: it seems much more contagious than that observed previously. And the devices undertaken to counter it today seem insufficient in the face of the virus which is currently circulating, observes Jean-Luc Guérin, professor of avian pathology and director of an INRAE laboratory of infectiology at the National Veterinary School of Toulouse. Because, for him, there are necessarily things put in place that have not worked well enough.
“We must not throw away what has been done, but among the instruments available, those which have been implemented have been exceeded in several regions of Europe at a given time”, as in the South-West of France, but also in Italy, or in Great Britain, he adds. The epizootic is European, the situation is “exceptionally serious” and the epidemic has become “out of control” by the admission of the Minister of Agriculture Julien Denormandie. For the professor, there are therefore different things to put on the table, particularly the three pillars which allow the control of animal epidemics: biosecurity, surveillance, and the link still missing in Europe, vaccination.
Improve biosecurity
Poultry farmers also have their “barrier gestures”. Biosecurity, i.e. the sanitary protection of farms, makes it possible to curb transmissions. Concretely, it is a question of separating the different farms from each other, avoiding contamination by truck or by people, “it is a kind of social distancing on the scale of the farms”, summarizes Jean-Luc Guérin.
This device, in which breeders have been trained, has “a braking effect, but can still let contamination pass. We thought that the application of these gestures should make it possible to control the infection, but we were overwhelmed in the South -West, now it is everywhere, he nuances.The more outbreaks there are, the more difficult it is to prevent new outbreaks from being created, especially since the presymptomatic phase is long in ducks, almost a week, allowing the virus to circulate unnoticed.”
This is also the opinion of Gilles Salvat, deputy director of the research division of the health agency Anses, interviewed by AFP: “Firstly, there is progress to be made on the observance of biosecurity measures, throughout throughout the year. This means changing boots and clothing when entering the farm, washing your hands, systematically disinfecting your equipment, not exchanging equipment with your neighbor without precaution, storing the straw under cover migratory birds.”
“Secondly, he has to think about the density of farms during the migration period, but also the proximity of farms to each other. Thirdly, we must limit transport distances: we have seen a case of contamination with animals transported over 80 km, from a village in the Landes to a village in Lot-et-Garonne”, he continues.
Strengthen monitoring
The second pillar is therefore transmission monitoring. The famous “test, trace” applied for a time to fight against the Covid-19 epidemic, with the difference that here, “we eliminate as quickly as possible the batches declared positive”, adds Jean-Luc Guérin. This monitoring has already been improved during the last avian health crisis, but it could be more effective.
Because “in a normal scheme, we manage to manage with these two pillars of biosecurity and surveillance” but “there are areas where we are less successful because there is a farm ecosystem that is very difficult to secure. does not mean that the breeders of the South-West apply these measures less well than the others, they are just in the wrong place at the wrong time and we find ourselves in a situation where we encounter great difficulty in preventing the fire from starting “, explains the professor of avian pathology.
On the other hand, there is no reason to target intensive farming in particular, according to him. Indeed, the Southwest is much more affected than other regions of France. However, this is not the area where there are the most intensive farms, much less than in Brittany or Vendée for example, which are not experiencing the current epizootic in the Landes. “It’s a problem of territories where the notion of ecosystem is very important”, explains Jean-Luc Guérin.
According to him, there is nevertheless “a margin of progress on the two pillars, but that will not be enough to prevent the phenomenon that we are experiencing today”. There remains then a third lever, which has never been activated in France or in Europe: vaccination.
And the vaccination?
It is a sensitive subject, “very badly perceived by the international veterinary community” according to Jean-Luc Guérin, and which is nevertheless acclaimed by breeders, like Philippe, interviewed by L’Express at the beginning of January. “I’m not a doctor, but I don’t understand why we don’t vaccinate our ducks. That would be the solution. With the Covid, we vaccinate humans well…”, he argues.
So why such a blockage at European level? Several countries, like China, Mexico or Vietnam, have already opted for this solution. But the countries which have made this choice “are suspected of poorly controlling the circulation of the virus and hiding the disease”, explains Jean-Luc Guérin. On the other hand, vaccination should not evade the other pillars, it is an addition to what is already undertaken. Because even vaccinated, infected animals could continue to transmit the virus, with few or no symptoms, which could favor a genetic evolution of the strain, towards a more pathogenic version again.
“For the moment, there is no vaccine with a marketing authorization against avian influenza. And even when there is, it should be added and not replaced the other preventive measures”, abounds Gilles Salvador. “At present, the vaccination of animals is technically delicate. Indeed, it must be guaranteed that the vaccine is well adapted to the viruses present in the zone considered and that the implementation of the vaccine does not promote the inapparent circulation of the virus. wild in vaccinated birds For Member States of the European Union, vaccination is prohibited because the available vaccine technologies do not allow it”, explains for its part the National Agency for Food, Environmental and Occupational Health Safety (Anses), on his website.
Nevertheless, the measure is on the table, says Jean-Luc Guérin, and discussions around the vaccination of animals against avian flu “have been reactivated in recent weeks. Experimental trials will be undertaken to evaluate this vaccine strategy, in a perspective of very targeted, supervised application in a given region and under close surveillance”, he says. He then evokes the vaccination of ducks, in winter, in the South-West region. “Without being a miracle solution, the vaccine would reduce the viral load and therefore contain the infection, provided that it is added to the two fundamental tools of biosecurity and surveillance”, he pleads again.
Certain elements also go in the direction of this preventive solution. The FAO (Food and Agriculture Organization of the United Nations) recommends in a notice of May 2016, vaccination against H5 strains: “In areas where Influenza is endemic, the vaccine has been used to reduce the viral load in the environment, which, in turn, reduces the risks of human exposure and the likelihood pandemic influenza or zoonotic influenza”.