Mexico will return to business as usual today after easing swine flu restrictions. The move is a positive one for the country, which is the known epicentre of the outbreak. Mexican Health Minister Jose Angel Cordova called an end to the precautionary five-day shutdown to "resume, as planned, activities in the public and private sector on May 6 with recommendations on matters of health and hygiene at the work place." Trade restrictions continue, however, with approximately 20 nations banning pork products from North America - Canada, the USA and Mexico - although there is no evidence to suggest the virus is food-borne. Canada has threatened to take China to the World Trade Organization unless the Chinese lifted its ban on pig and pork imports from Alberta, where a herd of pigs was found to have the H1N1 strain. Despite the end of Mexico's shutdown, health experts warn that the virus could re-emerge a few months from now and have a more devastating effect, like the 1918 Spanish Flu pandemic, which killed millions.