One of the suggestions we were given by the officials who were suggesting that this was the way to go--that is, to take land conveyances out of the bill--was that Americans, people from the United States, for the most part have similar health status to Canadians, and that the real threat comes from third world countries; for example, the SARS infection.
But we've just had a case in the news in the last 24 hours where the person who was putting others at risk was actually an American who was carrying a disease that was not normally thought of as something you would expect to come from the United States. He in fact was told by his doctor not to travel. He travelled anyway, got the results of his earlier tests while he was abroad, knew he would not be accepted into the United States because he was immediately put on the no-fly list, and flew to Canada instead in order to rent a car and drive home.
So it seems to me that this serendipitous--in my view--case, for our purposes, has proven that you can't name which country these germs are going to come from. They could come from anywhere.