New avian flu readily transmits in key animal model

Declan Butler in Nature: A study on the novel H7N9 avian influenza that has killed 36 people in China finds that the virus is transmissible between ferrets. According to the authors, the findings suggest that H7N9 could become capable of passing from person to person — although thus far the virus has not shown any signs of doing so.

The researchers, from China, Canada and the United States, inoculated six ferrets and four pigs with H7N9 isolated from a fatal human case in Shanghai. All the animals became infected. Counting humans, that makes three mammalian species that can be infected with H7N9. Tests on other species, including companion animals such as cats and dogs, could give a better idea of the host range of the virus.

The H7N9 virus carries mutations that enable it to infect mammals, including humans, more easily than the related H5N1 avian flu can. There has been an unexplained lull in new cases since 7 May, but experts fear that it is only temporary.

Infections in other mammal species could provide the virus with opportunities to mutate and to adapt further. Pigs can be co-infected with avian and human flu, allowing the viruses to swap genes to create new strains, although extensive sampling in China has found no pigs harbouring H7N9....

An electron micrograph of H7N9 from the Centers for Disease Control