Everybody assumes that the biggest killers of children in poor countries are diseases like cholera, pneumonia and dysentery and it's this belief that still drives the global public health agenda.
Yet it's not actually true.
In countries like Bangladesh, drowning is the number one killer and it's a leading cause of death in south-east Asia. There are a quarter of a million child fatalities from drowning every year - as many as all the children and adults who drowned in the Asian tsunami of 2004. Yet because most child drownings go unrecorded and because they happen in ones and twos every day, rather than in one great cataclysmic event, the problem has gone largely unreported. It's a hidden killer - a 'silent epidemic'.
Mark Whitaker reports from Bangladesh, and also from Vietnam where the problem was identified with the help of the first US Ambassador to the country after the war, Pete Peterson. An ex-fighter pilot who spent six years as a POW in Hanoi, Peterson founded The Alliance for Safe Children which led the research revealing the problem and now leads a large drowning prevention programme.
Children drown in these countries because there are so many ponds, irrigation ditches and rivers, often within yards of each house. Few know how to swim and the youngest are particularly vulnerable when mothers are too busy to supervise them closely. So in Bangladesh, a country that is 70% under water, TASC is pioneering a huge programme of "survival swimming", training local instructors to teach simple swimming strokes, treading water and safe rescue. For children under four, there's a parallel programme of village creches to keep them safe while their mothers do the chores.
Producer: Mike Hally
A Square Dog Radio production for BBC Radio 4.