To find out more about the health issues affecting migrants and what can be done to protect them, I spoke to Leen Lacroix, who works for the aid agency Médecins Sans Frontières (MSF) as coordinator for North Serbia, a key transit point for people on the eastern Mediterranean route. She tells me MSF is taking a two-pronged approach: treating people’s medical conditions, and setting up well-insulated shelters “to prevent medical issues becoming worse”.
Source: National Geographic, UNHCR, International Organisation for Migration, Regional Mixed Migration Secretariat
“We are finding many respiratory conditions linked to ... people being outside in the cold during the evening and overnight,” she tells me. Skin infections are also widespread “due to poor hygienic conditions during the long trip”. By the time they arrive, “people [have been] on the road between ten and 15 days, without proper water or shelter”. Opportunistic infections like pneumonia are spreading.
With blizzards and sub-zero temperatures due soon, MSF has been erecting large, highly insulated shelters that are raised off the cold, damp ground in the Balkans. It has imported special insulation material from snow-prone Norway — “the first time this material has been used in humanitarian situations”. The polystyrene-based fabric provides a thick layer of protection inside the existing tent.
The winter conditions demand more shelters, particularly those that use innovative insulation, to protect people from sub-zero temperatures. With borders constantly opening and closing, many refugees spend days waiting for access, “so we have to have a back-up plan for shelter”, Lacroix says.
MSF is also concerned about the rising numbers of highly vulnerable people making the journey. “Over the last weeks we have seen more and more families with really small children, disabled people with wheelchairs, and older people who are really having a lot of difficulties.
“We’re also seeing women who are seven or eight months pregnant who are taking the decision to move, and women with new-born babies.”
This evidence from the ground goes against expectations that the onset of winter would discourage travel. “When we talk with families, they say they spent months in Lebanon but the living conditions were not getting better,” Lacroix explains.
Meanwhile the UNHCR (the UN refugee agency) has launched an emergency appeal for $96 million to fund its ‘winterization plan’, including heated shelters for those passing through or stranded in Greece and the Balkans. 
UNHCR data confirms that, despite perilous sea conditions, the number of people crossing from the Middle East and North Africa to Europe is still rising: 220,000 people via the Mediterranean in October alone — more than in the whole of 2014.
Imogen Mathers is producer/assistant editor at SciDev.Net. @imogenmathers