Health officials are trying to establish whether outbreaks of a new flu strain could spread around the world and turn into a pandemic.The strain – which is said to be an unprecedented mix of swine, human and avian flu viruses – has killed up to 68 people in Mexico and infected eight others in the US. Mexicans are being encouraged to avoid crowds and wear a face mask, and officials say they have enough anti-viral medicine to treat those affected. The World Health Organisation says a global pandemic is possible, but it is too early to be certain. WHO Director-General Margaret Chan said: “I think at this point in time it is very important that all regions of the World Health Organisation work with our countries to heighten surveillance so that we know exactly whether this new disease is causing infection in human beings in countries other than the US and Mexico.” Alerts have been issued in various countries and precautions are being taken at some airports where flights from Mexico are landing. One encouraging sign is that Mexican doctors say they have not seen an exponential rise in the number of infections, as had been feared.