What animal may be infected by both human and bird flu?

Answer 1

For now the list is short of those documented to be able to get both:
Pigs, Humans, Birds

However, many strains of human flu are Type A Influenza. H5N1 Avian (Bird) Flu is a type A flu, and so is H1N1/09 Swine Flu. Many different animals get different strains of these Type A influenza viruses, but until recently, the transfer across species was not typical (rare or non-existent) and is still not very common.

Animals that commonly get Type A influenza strains are pigs, birds, sea mammals, horses, and humans. But so far only pigs and birds have been known to also get human influenza A which allows them to be a "middle man" for the cross species transfer of H5N1 to humans. There are no confirmed cases of human to human transmission.

There have been no cases of Bird Flu in animals or people in the US so far. It was in the UK for a period in some poultry, but it has been declared gone from the UK now. The cases of human infection with H5N1 are extremely rare world wide. Most cases have been in the East or the Middle East.

Bird Flu has also been known to infect other animals in rare situations in other parts of the world. The crossing between species requires that the infected animals and people (or animals with other animals) are living in very close frequent contact in overly-crowded conditions, these living conditions are not as common in the Western World.

There is also concern, but no proof, that other animals may be able to act as a bridge between birds and humans in flu transmission between animal species.

There have been a few cases of domestic cats infected from suspected ingestion of sick or dead birds who had the H5N1 virus. Some survived, some died. There have been no known cases of human avian influenza resulting from exposure to sick cats. But because cats are often in regular close contact and living indoors with humans, this is going to be an area requiring continued close monitoring by the public health officials of the world. There are also reports of big cats (tigers, etc.) in captivity having been infected with the Avian Flu. There are no reports of the big cats having it in the wild, however, so again, the crowding and frequent contact with other animals and humans in captivity is one of the major factors in that cross-over between species.

In addition to pigs, wild birds, pet birds, poultry, water fowl, humans, domestic cats, and at least one dog, other animals can be infected with Avian flu such as palm civets, cynomolgus macaques, New Zealand white rabbits, stone martens, tigers, leopards, ferrets and rats. It is believed that it is, therefore, possible that other mammals may also be susceptible to H5N1 infection, especially under the conditions of crowding.

The spread of the bird flu from humans to animals (including cats, dogs, and birds) has not been documented to date, but, in theory, could be possible under specific environmental circumstances.