Acting for the living: chronicle
David Grémillet, CNRS research director at the Center for Functional and Evolutionary Ecology in Montpellier, writes an ecological column for “”: “the Howling Albatross”. Today, the ravages and origins of avian flu.
It’s always the same refrain: wild birds bring us bird flu and are a threat to poultry farms. This message hammered home by the media effectively infiltrates our collective consciousness. This quasi-propaganda aims to make us forget the ethical, health and economic disaster of battery farms in industrial agriculture.
However, a scrupulous study of the scientific literature reveals another reality (1): even if mild forms of avian influenza have always been present in wild birds, battery breeding is indeed the evolutionary pressure cooker that has generated the variants. highly pathogenic. In particular, detailed studies have made it possible to very precisely identify the source of the first highly pathogenic form of the avian influenza virus (HPAI) circulating today.
This variant was born in 1996 on a goose farm in Guangdong province in southern China. The mutant then spread to wild birds, and occasionally to humans. At the time, the public authorities had already tried to blame wild birds, but scientific research clearly identified the poultry trade as the source of the problem. In particular, battery farms provide ideal conditions for the confinement of animals at very high density. This is due to the fact that high population densities, whether avian or human, increase the frequency of transmission events, and the probability of a mutation. Furthermore, the high density of hosts to infect favors high transmission, which is, in the case of influenza, linked to increased pathogenicity. Finally, outside of farms, transporting poultry over long distances quickly spreads dangerous viruses. Thus, avian flu initially colonized Chinese territory by following railway lines (2).
Since then, the HPAI virus has appeared in sixty-one countries and affects poultry farms around the world; it is now impossible to get rid of it. In 2021-2022, the most serious outbreak ever recorded on poultry farms, particularly in Europe, resulted in the culling of around 47.7 million captive birds. These dramatic events profoundly call into question intensive bird breeding, because of the intolerable animal suffering it causes, but also because rapid evolution in these confined spaces increases the probability of mutations leading to the emergence of HPAI as the next human pandemic. In this context, it is worth remembering that the genome of the Spanish flu, which killed more than 50 million humans in 1918-1919, was probably of avian origin.
Recent epidemics of HPAI in birds of the high seas, as far away as Antarctica (3), show that wild birds are the collateral victims of highly pathogenic avian influenza epidemics within battery farms. Some of these populations, already in danger of extinction following global warming and industrial fishing, have lost more than 90% of their remaining numbers in a few months.
For Amandine Gamble, infectious disease ecologist at Cornell University in the USA “We often hear that it is virtually impossible to control diseases that circulate in wildlife. In a case like that of avian flu, for which the origin of the disease is directly linked to our consumption habits, it is however possible to act before the disease reaches wildlife, by promoting health practices. breeding that does not facilitate the emergence of new variants of highly pathogenic viruses».
(1) Voir notamment : Lycett, S. J., Duchatel, F., & Digard, P. (2019). A brief history of bird flu. Philosophical Transactions of the Royal Society B, 374 (1775), 20180257.
(2) Gauthier-Clerc, M., Lebarbenchon, C., & Thomas, F. (2007). Recent expansion of highly pathogenic avian influenza H5N1 : a critical review. Ibis, 149 (2), 202-214.
(3) Banyard, A. C., et al. (2024). Detection and spread of high pathogenicity avian influenza virus H5N1 in the Antarctic Region. Nature Communications, 15 (1), 7433.
David Grémillet just published by Actes Sud In the arms of the octopuscollection of his columns published in for three years.
Source: www.liberation.fr
