Bird flu virus in foxes adapted to mammals

Recently, Wageningen Bioveterinary Research identified bird flu infections in three wild foxes in the Netherlands. The animals showed neurological signs caused by avian influenza of the virus type H5N1. Further analysis now shows that the virus in foxes has adapted to mammals. Moreover, it is remarkable that the virus was mainly present in the brain, while it is a respiratory virus.

Highly pathogenic avian influenza viruses of the type H5N1 currently cause a high mortality rate among wild birds in the Netherlands. Genetic analysis showed that the viruses in foxes resemble those found in wild birds. The foxes are probably infected by eating wild birds with bird flu. The study also found that the virus may have entered the brain through the olfactory nerve.

Two viruses isolated from the foxes contain a mutation associated with mammalian adaptation. The research shows that the mutated virus multiplies better in mammalian cells than in birds, and at the lower body temperature of mammals.

Infections in mammals should be closely monitored. The current virus cannot be transmitted between mammals or to humans, but further mutations could increase the zoonotic potential of the H5N1 viruses. Therefore, rapid detection of further mutations is important, as is avoiding contact with sick and dead birds.

More information can be found in the publication ‘Highly pathogenic avian influenza H5N1 virus infections in wild red foxes (Vulpes vulpes) show neurotropism and adaptive virus mutations‘ on bioRxiv.

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