A stage, lights, a mesmerised audience: it looks like an Egyptian folkloric concert but Umm Sameh is singing to heal the sick by driving out the demons that possess them. The music and dance ritual known as “zar”, with centuries-old roots in Ethiopia and Sudan, is traditionally performed to ward off or exorcise jinn or evil spirits. “We’re not quacks or witches,” said Umm Sameh, aged in her 70s, with kohl-lined eyes, large hoops swaying in her ears and gold bracelets tinkling on her arms. “The singing is spiritual and brings out negative energies,” said the lead singer of the Mazaher ensemble,…