-- In Somaliland, medical workers are in a desperate race against time to save millions of children from death.
The children are at risk of starvation in South Sudan, Somalia, Yemen and Nigeria. According to Carolyn Miles, the CEO of Save the Children, of the 20 million people at risk of starvation across the four nations, 10 million of them are children younger than 18 years old.
At the Burao Nutrition Stabilization Center in Somaliland, Muir and his team met with Dr. Yousef Ali.
According to Ali, the country is on the verge of famine.
"That's what I believe. That's what I believe," said Ali, the center's regional director of health. "We're seeing it here. I don't need a witness to prove it."
International refugee agencies say a humanitarian crisis is imminent.
Read more of David Muir's trip: A desperate plea for help as 4 African nations near a famine crisis
At one hospital, a nurse told Muir that a little girl named Hamda was so weak, the medical staff feared she'd die minutes after arriving at the center. Hamda was still holding on when ABC News arrived.
Dr. Jama Mohamed Ahmed told Muir he sees children like Hamda every day.
"They are dying ... due to severe dehydration," Ahmed said.
Yet the doctors and nurses in Somaliland continue to fight for their patients, even while conditions continue to worsen.
$10: Can help treat a malnourished child for two weeks (about two packets of Plumpy'Nut per day).
$15: Can help treat a malnourished child for nearly three weeks.
$20: Can help treat a malnourished child for one month or help treat two children for two weeks.
$40: One carton of Plumpy'Nut can help cure one child who is severely malnourished or treat four malnourished children for two weeks.