After the dairy cows, the pigs. While the epizootic, that is, an epidemic among animals, of bird flu ravaging the United States continues to spread at full speed on cattle and poultry farms, a pig tested positive for the H5N1 virus on October 29 in Oregon. This is a first for the United States and an additional warning sign, as these animals are known to be particularly favorable breeding grounds for rearrangements between viruses, including humans.
This first case was detected in a corral, where the pig lived promiscuously with birds that were not intended for sale. This type of pollution is not new and has already been observed in other countries, especially in Asia, but also in Europe a few years ago. “This event of passage of the flu virus in pigs is quite expected, but it must be monitored, because there is a real risk of reassortment”explains Gilles Salvat, deputy director general of the National Agency for Food Safety, Environmental and Occupational Health (ANSES). All flu viruses circulating among pigs are considered to have zoonotic potential, meaning they can infect humans.
the pigs have In fact, in its respiratory system there are receptors that allow the multiplication of viruses adapted to mammals, including humans, as well as avian viruses. A simultaneous infection by an influenza virus of avian origin, such as the one currently circulating in American cattle, and the human influenza virus could favor the genetic mixture of these two viruses and give rise to a new, potentially highly contagious pathogen. for the human being. In 2009, the influenza A (H1N1) epidemic was caused by the recombination of several viruses of swine, avian and human origin. This risk of co-infection is materializing a little more today, as the seasonal flu period begins.
“We have taken the alert one step further”
“Knowing that there has never been a human epidemic with an H5 subtype influenza virus, the human population has no immunity and would be totally naive, immunologically speaking, in the face of such a virus.” warns Gilles Salvat, specifying that this would be the “the worst case scenario”. This situation is not yet the most likely since, in the case of the H5 subtype, the pig is not a very effective host.
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