H5N1 avian flu has been detected for the first time in a pig.

The US Department of Agriculture says it was in a pig on a backyard farm in Oregon.

Pigs represents a particular concern for the spread of avian flu because they can become co-infected with bird and human viruses, which could swap genes to form a new, more dangerous virus that can more easily infect humans.

Pigs were the source of the H1N1 flu pandemic in 2009-2010. However, the finding the virus on a small farm makes the pig infection less of a concern than if it has been detected in a commercial hog operation. The Oregon farm is under quarantine and the other animals, including sheep and goats are under surveillance.

Wild bird migration has already carried avian flu to some poultry flocks and a handful of dairy herds in the United States.

(CJWW)