Kony video maker Jason Russell faces weeks in hospital

Jason Russell produced a video on the use of child soldiers by Uganda warlord Joseph Kony

Advocacy group Invisible Children's co-founder will be in hospital for weeks after he was found semi-naked and screaming at traffic, his wife says.

Jason Russell, 33, has been diagnosed with a mental condition brought on by stress or trauma.

Last week, police found Mr Russell screaming and running through the streets of San Diego, California.

He narrated the Kony 2012 video about child soldiers in Uganda that recently went viral on the internet.

Witnesses reported a man behaving bizarrely in the street, pounding his fists on the pavement and shouting incoherently.

Some people who called the police said the man was naked, although he was semi-clad when police arrived.

'Sudden transition'

The incident came after Invisible Children's 30-minute campaign video on the use of child soldiers by Joseph Kony's Lord's Resistance Army in Uganda suddenly took off on the internet.

It has been viewed more than 84 million times on YouTube in recent weeks.

Mr Russell's family has emphasised that his outburst was not brought on by drugs or alcohol.

Early diagnosis suggests he is suffering from "reactive psychosis", in which the patient shows psychotic behaviour without warning.

"Doctors say this is a common experience given the great mental, emotional and physical shock his body has gone through in these last two weeks.

"Even for us, it's hard to understand the sudden transition from relative anonymity to worldwide attention - both raves and ridicules - in a matter of days," said Mr Russell's wife Danica.

"He has a long way to go, but we are confident that he will make a full recovery," she added.

Invisible Children has the backing of countless celebrities and the International Criminal Court's chief prosecutor, but both the group and the video have also come under heavy criticism.

Activists say the campaign simplifies a complex issue, and questions have been raised about Invisible Children's financing.