With suspected cases cropping up worldwide, global concern is growing over the spread of swine flu.The World Health Organisation has raised its warning alert by one level to Pandemic Stage Four. A spokesman said that while this does represent a significant step towards pandemic influenza, it means it is not yet a foregone conclusion. “We think that we have taken a step in that direction but a pandemic is not considered inevitable at this time. The Director General recommends not closing borders or restricting travel. However it is prudent for people who are sick to delay travel,” said WHO spokesman Keiji Fukuda in Geneva. The organisation also urged governments to strengthen their preparations for the possibility of a pandemic. The flu virus spreads quickly between humans and although it has so far only killed people in Mexico, governments across the world are taking precautions to try and reduce its impact.