The number of tourists suffering from the syndrome always spikes around Christmas and Easter.
The clinical symptoms usually begin with a vague and extremely intense excitement. The patients often adopt "biblical" or otherwise eccentric clothing, sometimes merging their identity with that of a character from the Bible or having a strong feeling of mission. They typically adopt a lifestyle of religious observance and attach unusual significance to religious relics.
According to Reuters, psychiatrists disagree whether it can affect otherwise healthy people or causes only those predisposed to psychoses to believe they have seen the Messiah.
The syndrome was first diagnosed in the 1930s by Dr Heinz Herman, one of the founders of modern psychiatric research in Israel, and describes a large variety of extreme and excited behaviors and anxiety states exhibited by some visitors to Jerusalem.
Subsequent research was made by Dr Yair Bar El, former director of the Kfar Shaul Psychiatric Hospital in Jerusalem, involving 470 tourists who had been declared temporarily insane.
In an interview with the BBC, Dr Bar El revealed he had treated several Jesus Christs, a Virgin Mary or two, and Samson.
One of the most long-standing case studies is Californian Ernest Moch. He is known as Elijah and is convinced that he is a reincarnation of the original Prophet Elijah from the Bible.
During a walking tour of Jerusalem's Old City in 2003, tour operator Avi Green said a 19-year-old American participant saw the stones of the Western Wall, one of Judaism's holiest sites, open up and reveal the Messiah.
"He had a vision that the stones of the wall opened and the Messiah appeared and spoke to him," Green said. "He became delusional and violent."
Between 30 and 40 tourists each year are admitted to hospital for similar behavior, Dr Gregory Katz, head of the emergency unit at Givat Shaul Mental Health Centre, said to Reuters.
Most of the hospitalized visitors were Jews, but many others were Christians. Most patients are middle-aged with strong religious foundations.
Katz described the syndrome's progression in an article published in the British Journal of Psychiatry in 2000.
- The afflicted tourist becomes agitated, nervous and tense.
- The person declares a desire to split away from his or her group and tour Jerusalem alone. Katz warned tour guides to be aware of this symptom because after stage two, the progression is usually irreversible.
- The individual has the need to be clean and pure and will obsess about bathing and cutting fingernails and toenails.
- The person prepares a long, white, ankle-length, toga-like gown, often using a hotel sheet.
- The person feels the need to shout or sing psalms, verses from the Bible or religious hymns.
- The person marches to one of Jerusalem's holiest places, often along the Via Dolorosa or near the Western Wall.
- The psychotic traveler delivers a sermon at the holy place.
The episode lasts a few days, after which the person usually does not remember what happened.