When I was five, I left Singapore with my family to move to the UK, travelling by boat for six weeks. Had I boarded with one of the many strains of avian flu circulating then, as now, in Asia, I would either have recovered or died en route, infecting only other passengers. Today, I often travel between my workplace in Vietnam and the UK in less than a day. Were I to bring a new, transmissible infection, I would become a vector of potentially global concern.

With globalisation of travel has come globalisation of disease. The emergence?of?new viruses such as the H7N9?strain of flu, reported last week to have achieved human-to-human transmission in China, is no longer a matter for the regions in which they arise. What affects Shanghai or Ho Chi Minh City today can affect London or New York tomorrow.

For more than 17 years, I have worked in Vietnam on the front line of emerging infectious diseases, such as H5N1 bird flu, which hit the country in 2004; and Sars, which spread around the world in 2003. My experience makes me convinced that H7N9 is a cause for concern.