Rumours of a mysterious new disease; an apparently tardy response as people begin to die; controversy over swiftly escalating measures to bring it under control. The description applies to two events since the start of the millennium – and Margaret Chan has been at the centre of both.

In 2003, she was director of health in Hong Kong when severe acute respiratory syndrome (Sars) hit. This year, she has risen to international prominence as the director-general of the World Health Organisation, co-ordinating the response to swine flu.

Born in Hong Kong in 1947, Dr Chan initially studied home economics at college; few then would have predicted that commitment and political nous would propel her into the top job in international public health. Her experience has prepared her well for the current crisis, although questions remain over her broader agenda.