His eyes fixated me.

They bore right into my own, rarely blinking, as if reading my thoughts. Old eyes these, not those you would expect of a one-year-old child. Worldly eyes, damning, tender and terrified all at the same time. What these eyes had already witnessed I could only imagine.

What hardship, suffering, wickedness rather than the usual childhood wonderment had seared back through this youngster's gaze to give him this look?

His name was Yap Ji Kany, and his whole being seemed to me etched with anguish.

Perhaps his look came not so much from what he had seen as the pain and hunger this little boy was clearly enduring.

A feverish sweat streamed down his face, congealing where it collided with the cream smeared in a vain attempt to relieve the corrosive rash of a skin infection that had broken out across Yap's face and tiny body.

His mother, Nyaker, 23, sat on a plastic chair, Yap Ji perched on her lap. Surrounded by the stinking open sewers and tarpaulin tents of Tomping Camp bulging with other displaced families, I listened to their story.

They had come here to the capital, Juba, from the northern town of Bentiu. War, fear and above all that other horseman of the apocalypse here in South Sudan, hunger, had brought them from Bentiu's misery to this wretched United Nations Juba compound awash with rainy season mud.

Caught in the crossfire of bullet, shell and rocket fire between government and opposition forces in Bentiu, Nyaker, Yap and his brothers and sisters at first fled into the bush. Three days later, what little money the family had was spent and the pangs of hunger began to take their toll on the youngsters.

Nyaker had no choice but to steer her children through the frontline fighting to the UN compound in Bentiu, which like others elsewhere across the country are known as Protection of Civilian (POC) camps. At least here in the camp lay the chance of food.

"We saw lots of bodies, so many dead as we came from the bush into the camp," Nyaker recalls.

She and her family were not alone in what they saw. At the peak of the fighting in Bentiu, more than 38,000 hungry and traumatised people streamed into this swamp-like mini city.

"It may not be the biggest but it has to be one of the worst camps in the world, certainly one of the worst I've ever seen," said one veteran aid worker who for more than three decades has witnessed the worst of what Africa could throw up by way of humanitarian crises from Rwanda to Ethiopia.

In this "sanctuary", Nyaker and others waded knee-deep through lurid green water contaminated by raw sewage and human faeces. At times, so deep is the water here that lying down to sleep is near impossible. Any high ground is sought after; every patch is occupied with people sleeping, cooking, and always trying to stay out of the often lethally polluted water.

Mothers like Nyaker have been known to sleep sitting upright, their children lashed to their bodies, to prevent toddlers slipping into the putrid lake of filth surrounding them.

Conditions here ravage the health of adults and children alike. But it is the children who make up half of South Sudan's population and who suffer the most.

At one stage in this hell-hole, as many as 20 youngsters under the age of five were dying every week from pneumonia and diarrhoea, these diseases almost always underpinned by malnutrition.

"There was a little food in the camp that the aid groups gave us, but there was no charcoal for the fire to cook it," said Nyaker. She went on to describe another of Bentiu's horrors.

Every day in the search for firewood, Nyaker, like other women in the camp, ran the gauntlet of the marauding rapists among the ranks of armed men in the surrounding district. But not to make this trip meant the children going hungry. "Many women were raped, every day I went in fear and only by luck I was not taken by these men."

Nyaker said she then made the ­decision to try to leave Bentiu for another UN compound many days journey away in the country's ­capital, Juba.

It was not my first time in these Juba camps. Though many months had passed since my last visit, during which aid agencies had upped their on-the-ground response, conditions remained appalling. Overcrowding and the dire physical and emotional state of the people who arrive in these Juba POC camps leaves them extremely vulnerable to other dangers such as malaria and cholera that stalk these pools of human misery. And then there is the hunger, always the hunger.

Nyaker and her family had fled Bentiu in July, leaving the children's father behind. Like many civilian males he would have risked being killed had they encountered the armed men that control the endless roadblocks set up along the route of the family's long passage south along the near-impassable rainy season rust-coloured clay tracks that pass for roads here.

Roughly the size of France and with a population of around 11 million people, South Sudan has only 200 miles of paved roads, meaning that when hunger and humanitarian crisis threatens, the logistical problems of getting food to the most needy are immense.

"Sometimes the men with guns would stop us and make us give them lifts in the truck and we would sit in fear never knowing what might happen," recalls Nyaker of those nerve-racking days in transit.

As we sit talking outside the family's flimsy ramshackle shelter in Tomping camp, the sky above is full of grotesquely ugly marabou storks circling the fly-infested heaps of garbage that pile up inside the compound. Elsewhere, silhouetted against the thundery horizon, UN helicopters carrying food and other aid to remote outlying regions like Bentiu, Malakal and Bor lurch into the air from the congested runway of nearby Juba airport.

With its cloak-like wings and occasional large white mass of "hair" the scavenging, vulture-like marabous are sometimes known as the "undertaker bird".

Never was there a more appropriate name for a creature whose own existence in these camps seems to shadow the lives of those who live and die here.

Nyaker tells me she is worried about her children's health, and especially that of her youngest son, Yap Ji. "He's in so much pain from the skin infection. Many of the children have it from the puddle water that lies in the camps in Bentiu and here in Tomping.

"Always they are hungry, asking about food many times every day, but what I can do, there is so little to go round."

For some time now South Sudan has wavered back and forward on the verge of famine. In real terms this means that one-third of the country's 11 million people are facing starvation. The maternal mortality rate here is the highest on the planet, while on the Fragile States Index, which measures a nation's vulnerability, South Sudan has hovered near the top since it gained its independence in 2011; Sudan has been in a similar position for many years. Aid workers and nutrition experts now believe as many as 50,000 children could die by as early as next year in what would be the most devastating famine since 30 years ago this month when hunger gripped Ethiopia, resulting in a global response.

"The scale, depth, and ferocity of what has happened has engulfed this country as a tsunami would have done if we had a coast," says one of the senior UN officials who has led relief efforts in South Sudan.

Right now, whether a famine does or does not happen in the coming weeks and months depends on the immediate global response. It is, in effect, crunch time.

Those rainy season floods that have made life a misery for countless hundreds of thousands of people like Nyaker and her family living in the camps of Bentiu, Juba and elsewhere, are giving way to the dry season which now brings its own dangers and challenges.

Many South Sudanese I spoke with fear an upsurge in the violence as the warring groups in the country ratchet up the fighting during the coming dry season. The growing febrile atmosphere could wipe out recent gains in food security and push the number of severely hungry people up by one million in the first three months of 2015. In other words, South Sudan would rapidly move from crisis to catastrophe.

To enable them to cope with such a terrible worst-case scenario, and indeed respond to the current crisis, aid agencies are already gearing up their programmes.

To see for myself how such efforts are implemented beyond the nutrition programmes in camps like those in Juba and Bentiu, I flew to the country's remote northern Bahr el-Ghazal region and the areas of Aweil West and Aweil North.

As our plane journeyed north across the country, the scale and remoteness of South Sudan becomes all too apparent. Mile after mile there is no trace of anything resembling a proper road, no infrastructure to speak of.

Dropping down onto the dirt airstrip at Aweil into the furnace-like heat, we spend up to three or four hours a day driving out into communities along rutted dirt tracks. In the days that follow it becomes evident the extent to which people in these remote places live on the brink when it come to what aid workers call food security.

Food - its availability, production, distribution, impact on health, families and children - is the leitmotif for existence here. The spectre of hunger has been a constant threat for generations past and present, its vagaries dictating people's movements and life patterns, aspirations and fears.

Kiir Yum Kiir is 49 and no stranger to the way hunger stalks this land. Back in 1989, he and his family were forced through food shortages to flee into neighbouring southern Darfur. There, like so many of their countrymen and women over the years, Kiir spent time in a refugee camp facing the dangers of raiding bands of Janjaweed militia who killed, raped and looted.

Throughout all this time, finding enough to eat was a daily struggle. At one point, one of Kiir's own children was abducted by the Janjaweed, but luckily later returned.

It wasn't until 2006 that Kiir and his family returned to South Sudan, arriving back in their home community in Aweil with even less than they had in the refugee camp in southern Darfur.

"We had to begin from zero, with nothing, we had farming skills but no tools or seeds," he tells me as nearby his children sit listening, among them the son taken years ago by the Janjaweed.

Yet proof that lives can be turned around came when Kiir enrolled as a beneficiary on an aid agency's programme.

"Before this we would only have enough food to last us from the start of the year until March, but now because of the help we received from aid agencies, we can make the food last until the next harvest and even have a little surplus to enable us to improve our lives," he explains.

The remarkable thing about this change in Kiir's life is that it resulted from the provision of a simple metal plough which, drawn by a donkey, helps the family create just that little bit more of a crop yield, allowing them not only to eat and not go hungry, but also have some degree of food reserves and security.

"Life in 2006 was full of hunger and war, it has become better, but how sad and terrible it would be if once again these things were to threaten the people here in our community and across parts of South Sudan," Kiir points out.

He admits to fearing an escalation in violence during the coming dry season that might cause the famine so many humanitarian agencies are working hard to avert.

Time and again while in Aweil I am reminded of how fragile the prevailing situation is and the fine line that lies in preventing the widespread hunger that can so easily take hold.

At one very basic rural health facility, I watched as mothers and their young children, just like Nyaker and little Yap Ji Kany in the Juba camp, wait in line for a distribution of food and a nutritional assessment of their youngsters.

With the help of community health workers, some of the toddlers are loaded into a harness and scales for weighing, their physical condition closely monitored in an effort to keep them healthy and help fend of the other diseases to which they are so vulnerable.

For now aid agencies are fighting a daily battle to keep swathes of South Sudan from the abyss of famine the likes of which has not been witnessed for decades.

In this long-suffering part of the world there is a local proverb that says: "When God made Sudan, he laughed." The irony of the proverb's meaning is all too true. Right now, there is nothing to laugh about when it come to the predicament South Sudan faces.

Should the worst happen in the months ahead and hunger take its deadly grip here, then there is no point in us crying "not again".

The means to prevent countless children like tiny Yap Ji Kany from looking out on a world filled with pain lies in our hands.