There is nothing unusual about mammals contracting bird flu. Gray seal, European otter, red fox, lynx, raccoon, grizzly bear or badger: Although the phenomenon is rare, it has already been observed. But the more frequently it occurs, the more the virus mutates and is likely to spread, particularly to humans.
A virus that adapts to mammals
This probably happened last October at an American mink farm in Carral, Spain. According to a January 19 Eurosurveillance report, “genetic sequencing showed that the animals were infected with a new variant of H5N1, which contains genetic material from a strain found in seagulls and a genetic alteration known to confer the ability some animal flu increases viruses to multiply in mammals. »
So far, all known infections in mammals have occurred through “direct contact with contaminated material: animals ingesting wild bird droppings or feeding on infected animals…” This is probably how the virus got to the Carral farm, but what has never been heard, is that it then spread among the minks, from hotspots of two to four stalls, where all animals became infected and died. The 51,986 mink were then slaughtered on the farm.
risk of transmission to humans
If the 11 farm workers in contact with them all tested negative, the authors of the report draw a very important lesson. Because mink are “susceptible to avian and human influenza A viruses, […] This species could serve as a potential mixing vessel for interspecific transmission between birds, mammals and humans.”
This concern is also raised by the case of a family cat in Deux-Sèvres (New-Aquitaine), which was euthanized last December after contracting avian influenza. “The susceptibility of cats and cats in general to HPAI virus has been known since 2004,” according to the ANSES (National Agency for Food, Environmental and Occupational Health Safety), which cites cases in Thailand and Germany in particular in 2006. But “this is the first time such contamination has been observed in France,” adds the agency.
As in the case of mink in Spain, “the virus detected in this cat has genetic characteristics of adaptation to mammals,” explains ANSES, which indicates that only the cat carried this mutant virus, which was not found in ducks from the farm on origin of the contamination. The agency therefore warns of “the contamination of pets such as cats, which could facilitate transmission of the virus to humans”.