Staring blankly about his hospital ward, former South Sudanese soldier Ajing Deng has not been the same since getting caught in an enemy bombing raid earlier this year.

He is oblivious to all that goes on and only reacts when a nurse tries to give him another tranquilliser shot.

"Sometimes I sedate patients to stop them from moving," said Juba's military hospital head nurse Philip Oluru.

Deng, 30, suffers from post-traumatic stress disorder (PTSD). He is one of the countless people in South Sudan bearing invisible scars from his country's decades-long civil war with neighbouring Sudan.

Despite hosting one of Africa's longest running and bloodiest conflicts that has killed an estimated 2 million people and displaced many more, the new nation has neither psychiatrists nor health facilities to treat cases like Deng.

Deng was among the troops from the South who marched to Heglig, a disputed oil-rich area between Sudan and South Sudan, in April. With no aerial support, the soldiers from Juba were bombed incessantly by Khartoum.

The ex-combatant is still to recover from the experience.

"The patient started talking to himself, that's why they brought him here. We treated him with typhoid and malaria drugs at first but saw no improvement," Oluru says, adding that Deng was initially presumed to have fever-induced hallucinations.

But then Deng became restless and couldn't sit still, Oluru said.

"We tried to tie him down but it didn't work," he says.

Deng's case is far from unique among South Sudan's battle-weary military, officials say.

"Cases of post-traumatic stress disorder are many within the Sudan's Peoples Liberation Army. We have so many cases... we cannot help," says Peter Ajak Bullen, director of the military hospital.

Mental health patients admitted to the hospital have very few options in terms of treatment: sedation and basic counselling from three hospital staff with some training in psychology.

"This is only a short-term solution. It is not enough. Most of these patients are depressed, suicidal and with violent, murderous traits," Bullen says.

For some of these traumatised patients, suicide has become the only way out.

"Soldiers just shoot themselves," says psychologist Amasi Ibrahim Adam as she wearily makes her rounds through the wards.

Bullen, the hospital director, knows all too well the dangers that mental health disorders pose in the battlefield.

"In the front line... there are many cases of a colleague shooting another. It's just because of depression," he says shaking his head.

"Almost every two weeks there are reports of someone committing suicide or killing someone else. It's a big problem", says South Sudan's military spokesman Philip Aguer.

For civilians suffering from mental health issues here the situation is equally grim.

In a tiny ward in Juba's public hospital, patient Mathew Hakim is handcuffed to the bed. Despite being heavily sedated, he still manages to scream out snatches of garbled sentences about an Israeli invasion.

"We only have 12 beds. Aggressive patients are taken to the sanatorium at Juba prison," says senior medical officer George Wani.

Deputy Health Minister Yatta Yori Lugor says that recognition of mental health problems usually extends only to the most obvious cases, such as the naked people who can be seen wandering and shouting in Juba's streets.

That means that many cases simply go undiagnosed.

With security taking up a large percentage of official expenditure and aid agencies struggling to provide the most basic services, there have been no resources for working out official figures on the number of people affected by PTSD.

The only certainty however, is that the newly formed country is unable to properly care for those afflicted.

"Depressed people don't need these tranquillisers. They don't need prison. They need anti-depressants that we don't have," says medical officer Wani.