Jerusalem syndrome is an umbrella term for religiously themed delusions and psychotic episodes triggered by a visit to the city, and it crosses Christian, Jewish and Muslim lines and sometimes affects secular visitors. The pattern long predates jet lag. The 15th century itinerary of Dominican monk Felix Fabri describes pilgrims wandering the hills reenacting biblical suffering, and English mystic Margery Kempe, around 1413, wept so loudly at the holy sites that she alienated her fellow travelers. Nineteenth century writers called it Jerusalem fever and dismissed it as hysteria until psychiatrist Heinz Herman began documenting cases as clinical events in the 1930s. The syndrome still appears in neither the DSM nor the International Classification of Diseases.

In 2000 Bar-El and colleagues published three types in the British Journal of Psychiatry: people with prior psychotic illness who travel because of their delusions, people with intense idiosyncratic beliefs short of psychosis, and previously healthy tourists who break suddenly and recover after going home. Kalian and Witztum attacked that third type, noting there were no records proving those patients had been well. Kfar Shaul Mental Health Center saw about 100 affected tourists a year from 1980 to 1993, roughly 40 admitted, against about 3.5 million annual visitors. Bar-El predicted a millennium epidemic, hospitals set up triage, and it never came. The city, the critics argue, supplies the imagery but not the illness.

• Fabri’s pilgrims searching for nonexistent relics in the 15th century
• Type three patients bathing compulsively, cutting hair and nails, and preaching in togas made from hotel sheets
• Why 40 hospitalizations out of 3.5 million visitors matches ordinary background rates of psychiatric crisis
• Pop culture uses from a 2010 Simpsons episode and The X-Files to Black Box, a Joshua Sobol play and Neil Gaiman’s Trigger Warning
• A 2016 Metropolitan Museum of Art catalog that opened with the syndrome as a metaphor for the weight of history