Atlanta ? A study of duck hunters in Iowa is believed to be the first to show people can catch bird flu – a non-threatening kind – from wild birds.

Previous cases of people being infected with any form of bird flu have involved domestic poultry, like chickens.

The type of bird flu seen in the study is not H5N1, the deadly form that emerged in Asia which has sparked concerns of a potential worldwide flu epidemic. Rather, it is H11N9, another form seen in ducks and other waterfowl that has not been associated with human illness.

In the Iowa study, one hunter and two state environmental workers tested positive for the virus, though none of the three men got sick, said Dr. James Gill, the University of Iowa researcher who led the study.

Federal health officials say the finding is noteworthy. Domesticated birds – like chickens – are an established source of bird flu transmission to humans, but this is believed to be the first documented case of a person getting such a virus from a wild bird.

However, it’s not clear from the paper whether the virus was spread through blood, water or by other methods.