I'm assuming pretty much every other egg laying bird has the disease, even many egg laying reptiles (keeping snakes out of the chickens house is never any fun).
There was a big salmonella problem with ducks in the UK many years ago (1930s?) so people switched to eating hens eggs instead. Clearly the problem was much bigger in mass production, as then hens got it. So I think actually most birds do not have it normally.
