A new deadly flu virus suspected of causing more than 80 deaths is causing growing alarm in Mexico and around the world.Mexican authorities have urged people to stay at home as they try to halt the spread of the swine flu sub-strain that experts fear could become a global epidemic. Of the 81 people who have been killed, 20 have been confirmed as flu deaths – but health officials are on alert with more than 1,300 people believed to have been infected. Appealing for calm, Mexican President Felipe Calderon said: “Due to the fact that this is a new virus, something that is fundamental is to prevent this from becoming a pandemic, but it has a cure. It can be cured, it can be treated and we have the medication to cure it in large supplies.” Mexico might have enough antiviral medicines but as there is no vaccine yet Calderon’s message of reassurance has done little to stem a rising tide of panic buying in case the problem gets worse. France and New Zealand are the latest countries to report suspected cases. With the disease said to be highly contagious, other countries may start screening people who have just returned from Mexico.