To most, smelling another person's flatulence is an unpleasant experience.

But the world's first case study of a man who is sexually aroused by other people passing wind has now been published.

A British psychologist has recorded the case of so-called "eproctophilia" in a 22-year-old man from Illinois, America.

The man, who has been given the pseudonym Brad, states that he is "not sexually attracted to flatulence per se, (but) the person releasing the flatulence".

Professor Mark Griffiths, a lecturer at Nottingham Trent University, wrote about the case in the journal Archives of Sexual Behaviour.

Brad, who has a degree in fine arts, describes his first experience of eproctophilia - when he heard that a girl that he had a crush on in school had passed wind during a lesson.

"This blew my mind," he said.

"Prior to that, I'd never really considered it. I knew by simple biology that girls farted, but hearing that the girl I had been fawning over was capable of such a thing sparked a strange interest in me."

He said that he engaged in his first act as a 16-year-old when he heard a male friend pass wind in front of him.

He said: "It was rather appealing in sound and I found myself fixating on it.

"At first, I didn't want to admit I was into his farting, but eventually I decided to experiment. I set up a bet at some point and intentionally lost, with the wager being the right to fart in the loser's face for a week. I continued to lose such bets once every few weeks for about two years."

He said he enjoys both the "sound and the smell" of flatulence.

Professor Griffiths said: "Eproctophiles are said to spend an abnormal amount of time thinking about farting and flatulence and have recurring intense sexual urges and fantasies involving farting and flatulence.

"The prevalence and incidence of eproctophilia is assumed to be negligible given that no previous case studies have ever been published.

"Most people probably view flatulence as a disgusting behaviour yet eproctophiles do not."