Canada stepped up its screening measures at airports Tuesday to check passengers returning from Mexico for swine flu symptoms amid news that the virus has now infected 13 Canadians in four different provinces.
Seven new cases were confirmed Tuesday -- two in Alberta, four in Ontario and one in British Columbia -- adding to six announced Sunday. All have links with travel to Mexico, where the illness is suspected of killing more than 150 people and of sickening more than 1,600.
Swine flu has now spread far beyond Mexico however, with more than 80 cases now confirmed in the United States, Canada, Spain, Scotland, Israel and New Zealand. There are also suspected cases in many more countries but laboratory tests have not yet confirmed whether they are cases of swine flu.
British Columbia now has a total of three swine flu cases.