Extended drought is causing a food crisis in the Horn of Africa, which includes Kenya, Ethiopia, Djibouti and Somalia. Weather conditions over the Pacific mean the rains have failed for two seasons and are unlikely to return until September.

Since the beginning of 2011, about 15,000 Somalis each month have fled into refugee camps in Kenya and Ethiopia, looking for food and water.

More than 370,000 refugees are already crammed into three camps at Dadaab, built for a combined capacity of 90,000.

Many of the arrivals have walked for days or weeks, desperate to escape not only from the drought in Somalia but also its long civil war.

The children especially are malnourished and dehydrated when they arrive. Some die within a day.

Children aged five and under are especially vulnerable to malnutrition and the illnesses that frequently accompany it, such as pneumonia and diarrhoea. Here, two-year-old Aden Salaad looks up toward his mother as she bathes him in a tub at a Doctors Without Borders hospital.

The malnourished children receive high-energy food. Babies are also measured and weighed.

Aid organisations say they are over-stretched. It can take between seven and 12 days to deliver the first food rations to the camps.