[ti:] [ar:] [al:] [00:00.00]The United Nations top health official [00:03.67]has said the worldwide spread of swine flu is now unstoppable. [00:07.64]Doctor Margaret Chan was speaking at a global forum in Mexico [00:11.57]where the virus first took hold. [00:13.35]Andy Gallacher reports. [00:14.82]The head of the World Health Organization [00:16.86]was keen to promote Mexico as a safe destination [00:19.35]despite its suffering the largest number of fatality [00:22.41]since the outbreak began over two months ago. [00:24.85]Leaders and experts from across the world here in Cancun [00:27.85]to see what lessons can be learnt so far [00:30.19]but the advice is still the same. [00:32.53]The best way to avoid catching the virus is simple: [00:35.49]wash your hands and avoid coughing [00:37.72]and sneezing in public.