NAIROBI, Kenya -- On Aug. 13, Kuwa Hassan’s mother carried him to the German Emergency Doctors Hospital in a rebel-held area of Sudan. Four years old, Kuwa was feverish – suffering from diarrhea – and he weighed less than 16 pounds. He was barely alive.

The clinicians treated him for severe malnutrition and nursed him back to life. They put his three siblings on a feeding program. But when the time came to release them, the mother said there was no food back home, only leaves or other wild greens.

"I think they are going to be staying with us for a while," said Raphael Veicht, who runs the organization’s hospital and three clinics in the war zone.

Last month, global leaders congratulated Sudan and South Sudan for signing agreements to demilitarize their disputed border and to restart oil production and exports.

But the deal didn’t address the most pressing crisis in either country: the ravaged war zones on Sudan’s side of the border, where old conflicts broke wide open last year after South Sudan became independent, spewing out 200,000 refugees and trapping hundreds of thousands more in a cycle of hunger and fear largely unseen by the rest of the world.

Now, with a covert American aid operation blocked by muddy roads and no progress on ways to bring help to the conflict zones, the humanitarian situation is worsening, medical workers reached by Skype and email say. The Sudanese government continues to block official humanitarian aid into the border areas controlled by a South Sudan-friendly rebel group, the Sudan People’s Liberation Movement-North.

Veicht oversees one of the two hospitals in the Nuba Mountains, where the rebel hold is the strongest. Dr. Tom Catena, a Roman Catholic missionary from upstate New York, runs the other.

In conversations before and after the Sept. 27 agreement, Veicht and Catena described rising malnutrition rates, reports of starvation, and a ravaged and displaced civilian population that lies out of the reach of their medical care.

The signs of hunger began growing in April, when Catena’s hospital admitted 11 malnourished children. That number has kept rising, and in September 35 children were admitted for malnutrition, 26 others were put on a feeding program and there were 32 malnourished adults.

Veicht reported that his hospital and clinics fed 133 malnourished children in September.

And that’s only a symptom of the problem, both men think. Most of the population of the rebel-held Nuba Mountains is beyond the reach of either hospital. Even for the roughly 100,000 civilians who are within a day’s walk of medical care, many are too weak to make the journey.

Veicht said that when he traveled to Kuwa’s village of al Azarak last month – about 25 miles away by walking paths – residents told him that children had been dying from "weakness."

"What I can say for sure is that people are really, really skinny up there, and they do look really wasted," said Veicht, who compared them to the famine victims he saw last August working in Mogadishu, Somalia.

The Nuba Mountains may not even be the worse of the two Sudan People’s Liberation Movement-North battlegrounds. Some 140,000 people have poured out of Sudan’s Blue Nile state, where the Sudanese government has been conducting a scorched-earth counterinsurgency campaign that includes torching villages and poisoning wells.