For the purposes of this article, then, a "fugue state" occurs while one is "acting out" a "dissociative fugue". The DSM-IV  defines "dissociative fugue" as:

sudden, unexpected travel away from home or ones customary place of work, with inability to recall ones past
confusion about personal identity, or the assumption of a new identity
significant distress or impairmentThe Merck Manual  defines "dissociative fugue" as:

One or more episodes of amnesia in which the inability to recall some or all of ones past and either the loss of ones identity or the formation of a new identity occur with sudden, unexpected, purposeful travel away from home.In support of this definition, the Merck Manual  further defines dissociative amnesia as:

An inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by normal forgetfulness. Prognosis
The DSM-IV-TR states that the fugue may have a duration from days to months, and recovery is usually rapid. However, some cases may be refractory. An individual usually has only one episode. Cases
Shirley Ardell Mason (1923–1998), also known as "Sybil", would disappear and then reappear with no recollection of what happened during the time span. She recalled "being here and then not here" and having no identity of herself; it was claimed by her psychiatrist, Cornelia Wilbur, that she also had dissociative identity disorder. Wilburs diagnosis of DID was disputed by Wilburs contemporary Herbert Spiegel.
Jody Roberts, a reporter for the Tacoma News Tribune, disappeared in 1985, only to be found 12 years later in Sitka, Alaska, living under the name of "Jane Dee Williams". While there were some initial suspicions that she had been faking amnesia, some experts have come to believe that she genuinely experienced a protracted fugue state. David Fitzpatrick, who had dissociative fugue disorder, was profiled in the UK on Fives television series Extraordinary People. He entered a fugue state on December 4, 2005, and was working on regaining his entire lifes memories at the time of his appearance in his episode of the documentary series. Hannah Upp, a teacher originally from Salem, Oregon, was given a diagnosis of dissociative fugue after she had disappeared from her New York home in August 2008 and was rescued from the New York Harbor 20 days later. News coverage at the time focused on her refusal to speak to detectives right after she was found  and the fact that she was seen checking her email at Apple Stores while she was missing. This coverage has since led to criticism of the often "condemning and discrediting" attitude toward dissociative conditions. On September 3, 2013, she went into another fugue, disappearing from her new job as a teachers assistant  at Crossway Community Montessori in Kensington, Maryland. She was found unharmed September 5, 2013, in Wheaton, Maryland.