Jerusalem clergymen and officials came together Monday to discuss ways to spot and deal with the mental illness, which one psychiatrist says may strike as many as one in 100 pilgrims and disrupt Jesus' 2000th birthday celebrations.
About 4 million Christian pilgrims are expected to visit Israel and the Palestinian areas in 2000.
``There are feelings (in Israel) that this could turn a national celebration into a national nightmare,'' said Clarence Wagner, director of Bridges for Peace, a group that advocates close ties between Christian groups and Israel and sponsored Monday's discussion.
Trying to allay such concerns, Monsignor Richard Mathes, the Vatican's cultural attache in Israel, said that in 20 years in Israel, he had only seen two Catholics suffering from the syndrome.
Protestants are more vulnerable, apparently because their beliefs are less structured than those of the Catholics, Mathes said.
The Jerusalem mental health commissioner, Dr. Yair Barel, who first diagnosed Jerusalem Syndrome, predicted about 40,000 millennium pilgrims might suffer from religious delusions.
Of those, some 600 to 800 pilgrims may need to be hospitalized and some may become dangerous, Barel said.
``The danger exists that someone will try to do something very violent,'' Barel said. ``But the appropriate authorities are thinking about this and dealing with it.''
Israeli authorities had a taste of religious extremism fueled by millennial fervor when a Denver-based cult, the Concerned Christians, moved to Israel several months ago.
Police kept the group under surveillance, suspecting its members were plotting to carry out violent acts near holy sites to hasten an apocalypse and the Second Coming of Christ.
Cult members, who have denied wrongdoing, were eventually detained and deported to the United States, but have pledged to return.
One of Barel's recent patients, a Cincinnati school teacher, began showing symptoms after visiting the Church of the Holy Sepulcher where tradition says Jesus was buried and resurrected.
Two days after arriving in the city, the teacher began washing himself and shampooing his hair in a desperate frenzy to make himself pure. He fashioned his hotel sheets into white clothing and began shouting psalms.
The man recovered after a few tranquilizers and calls home, Barel said.
In Jerusalem's City Hall, officials deal with Jerusalem Syndrome as seriously as they do with traffic jams and overcrowded holy sites.
``We are very aware that some people may take (violent) actions,'' said Michael Wiel, a consultant working with the municipality. He would not provide details.
Mathes said that a visit by Pope John Paul II, which Israeli officials say is set for March, could bring more religious fanatics to Israel.
``We fear radical groups may use this visit to do something,'' Mathes said.
However, he said he believed the Israeli authorities are well prepared and will be able to prevent any violence at holy sites.