A fable inspired by the author Jesse Ball’s late brother, who had Down’s syndrome, has won the Gordon Burn prize.

The American author’s Census, which follows a terminally ill father and his son as they conduct a survey of a nameless country, beat works including Guy Gunaratne’s Booker-longlisted novel In Our Mad and Furious City to the £5,000 award at the Durham book festival on Thursday evening. The prize is for work that follows in the footsteps of Burn – “novels which dare to enter history and interrogate the past; non-fiction adventurous enough to inhabit characters and events in order to create new and vivid realities” – and has been won in the past by writers including Paul Kingsnorth and Benjamin Myers.

Ball said: “From the first, [Census] was for my brother, a person who no longer exists (he is in the ground)”. His brother Abram died at the age of 24.

“As his, it is a book pointed at a world that we do not live in, but perhaps could,” the writer said. “I would like for people to read the work because I think we can see differently than we do. We need not be limited by the poverty that is forced upon us, when we are already, every one of us, so rich in sight.”

Artist Gillian Wearing, who was one of the judges for the prize, described the experience of reading the “beautiful, moving” Census as “like walking through someone’s surreal grieving mind as they attempt to make sense of existence”.

Carol Gorner of the Gordon Burn Trust said Ball was a very fitting winner. “Gordon Burn cared deeply about writing style,” she said, “and he also cared deeply that those people who aren’t obvious subject matter should be written about. This strange and beautifully written book is perfectly matched to the aims of the prize.”