Tens of thousands of children roam the streets in Angola as a result of war, displacement, disease and other terrors. Nelson ran away because his family tortured him, accusing him of sorcery. Bacongo people from north-east Angola harbour tremendous fear of witchcraft. Last-born sons are often suspects. Horrifically abused young boys are sometimes tortured to death.
Nelson was held down by his parents, while a local witchfinder beat him and branded him with a hot iron. As in Medieval Europe, survival of such rituals is taken as evidence of guilt, and he was lucky to escape.
Many at the centre faced such ordeals; some were picked up half-dead. Like child soldiers, these children are harder to rehabilitate and reintegrate into their families than those who ended up on the streets because they were orphaned or displaced by war.
Fr Horacio Renaldo, a charismatic Argentine missionary, complains: "The worst thing is that the children start believing these accusations. Because of all the psychological pressure and beatings, they start believing they really are involved in witchcraft." Currently caring for some 250 boys, Fr Renaldo worked with street kids in Latin America before coming to Luanda in 1993. He established the current centre three years ago, financed by BP-Amoco.
Nelson described his rehabilitation, starting with an exorcism helped by a care worker: "I took some bread and put my sorcery inside it. I made a sandwich and put it in the ground. I told Sister she could leave it there, give it away, do what she liked with it. It was now hers. It didn't belong to me anymore."
He is one of the lucky few to graduate from street urchin to registered "displaced minor" and to be cared for in such a well-run centre. Thousands more destitute children wander the streets, living in sewers and rubbish dumps, constantly threatened by violence, drug addiction and vice, illiteracy, malnutrition and disease. Around one in three Angolan children die before their fifth birthday.
Across the city, at the prosperous island beach resort, the atmosphere is somewhat different. The country's elite have had a good war and have held on to their spoils, paying $200 (pounds 127) a head to attend the 1999 Miss Luanda competition.
Well-heeled Luandans were careful not to appear too enthusiastic as they delicately consumed fresh lobster while a succession of beautiful women strutted across the stage. Distracted from the filth and squalor around them, few noticed Angola being nominated the worst place in the world to grow up.
The Child Risk Measure in Unicef's Progress of Nations report traces five indicators: under-five mortality rate; malnutrition; school attendance; HIV prevalence, and conflict. Angola ranks worst in most categories, ahead of Sierra Leone, Afghanistan and Somalia.
Potentially one of the richest countries in Africa, vast oil and mineral reserves were squandered on decades of conflict. Civil war followed the anti-colonial struggle and the departure of the Portuguese in 1975. South Africa became involved, then came Cuba and covert American support for Jonas Savimbi's Unita (Uniao Nacional para a Independencia Total de Angola) rebels.
A relic of the Cold War and apartheid, Savimbi never really stopped fighting the victorious Movimento Popular par Liberacao de Angola (MPLA), despite several peace deals and the offer of the vice-presidency. Comprehensively defeated at the ballot box, he still believes the presidency is rightfully his, and is using control of the diamond fields to buy sufficient weapons to fight his way there.
A 1994 peace accord was supposed to end the conflict with a power-sharing agreement. Unita's failure to observe its provisions, and the deepening involvement of both sides in the Congo war, led to last December's full- scale resumption of hostilities. Savimbi controls most of the countryside; the government, most of the population.
The UN plans to embargo Unita's weapons supplies and annual $500m illicit diamond trade, but it will take time to break its stranglehold on the cities. With aid donors focused on Kosovo, relief agencies struggle with huge funding deficits.
Many believe the government also bears responsibility for the mess, and is only too willing to use Savimbi's intransigence to avoid meaningful political and economic accountability and reform. Most locals view the conflict as rival elites fighting for the spoils of office. While politicians battle for power, the masses are left to fend for themselves.
Unicef's Anthony Bloomberg regards the Child Risk Measure as "more an advocacy device than a scientific tool. The purpose is to send out alarm signals. We would like the government to sit up and pay more attention. We need to prevent children's lives being mortgaged into the future. Otherwise, the structural damage of so many children severely malnourished, badly educated and living in squalor will affect lives for generations."