Migrants struggle in sub-zero temperatures
Medics working at refugee aid camps in the Balkans say they are seeing a spike in the number of migrants falling ill as freezing temperatures arrive.
It has fallen to as low as -11C in the region.
The medical charities International Medical Corps and Medecins Sans Frontieres say most patients are suffering with respiratory problems such as bronchitis and flu.
There are also concerns about people refusing or not seeking treatment.
Migrants are offered medical assistance, warm clothes and food at the main refugee points at the Serbian border with Macedonia to the south, and Croatia to the north.
International Medical Corps runs a makeshift clinic at the train station in the tiny town of Sid, in northern Serbia.
"Last week, when temperatures were a bit less, we were seeing around 50 to 60 people a day," said Sanja Djurica, IMC team leader.
"This week, now that temperatures have fallen, it's more like 100 or so a day."
"Almost all of them are suffering with respiratory illnesses brought on by the cold."
'Journey of death'
I met the Al-Maari family, who are making the journey as the snow falls thick and fast. They fled Syria three weeks ago, and have been on the road ever since.
They are travelling with four children, the youngest is just two years old. His brother Mohammad, seven, is suffering with fever and a chest infection.
"We are on a journey of death," said Mohammad's uncle, Iyad Al-Maari.
"We can endure. But I am worried about the children - the cold, disease and hunger."
Mohammad is not thought to be seriously ill. Iyad said the family are determined to continue to Germany, where the children's father is waiting for them.
"Some people are refusing further medical help after we've assessed them," said Tuna Turkmen from MSF in Serbia.
"Even if they are referred to hospital, most don't go. They just want to keep moving... in case borders suddenly close and they are left stranded."
Need for emotional comfort
With tears in her eyes, Mohammad's mother, Malak, said: "We didn't want any of this… we just want the war to end in Syria."
The stress and anxiety can be seen clearly on Malak's face. She is traumatised and desperate.
Medics have also highlighted the enormous psychological impact on those making these journeys.
International Medical Corps has psychologists on hand in Sid, and even though people only tend to stay there for a few hours, medics and aid workers do have some time to deliver "psychological first aid".
"It's emotional comfort, empathetic listening and encouraging coping techniques," said Sanja Djurica.
"They are grateful just to have someone who will listen to them."