With some 12,000 migrants massed at the Greek-Macedonian border, the most vulnerable residents of the makeshift refugee camp there are suffering the most.
Living in filth and exposed to the elements, with food and water in short supply and sanitation facilities scarce, children are falling ill - among them Hani from Iraq.
For the last two days, she has been unable to keep anything down for more than ten minutes, whether it is water, tea or food, explains her father, Hazi Mohammad.