There was a time after the Second World War when it appeared that the virus of anti-Semitism had been contained.
The ghastly murder of six million European Jews, along with millions of other victims of the Nazi regime, gave rise to the post-Holocaust expression "Never again!"
In the process, the once prevalent suspicion, even hatred, of Jews began to subside.
Not that it diminished everywhere, mind you. In post-War Soviet Union, Stalin seemed to grow even more anti-Semitic and, in Poland, there were the occasional killings of returning Jewish refugees.
But in the aftermath of the Second World War, the Jewish people had their own state and refugees from Europe and Arab lands began to find their way there. As well, Jews in the broad diaspora began prospering in what many saw as the "promised land" of North America.
In Canada, where signs used to hang in some hotels and public pools — "No dogs or Jews allowed" — earlier prejudices gradually began to fade. Banks, law firms, businesses, hotels started to open their doors.
The notion of the Jew as the "other" began to disappear.
The new anti-Semitism
But the virulence of the virus that is anti-Semitism is never far from the surface and it breaks out in the most unsuspecting places.
In Canada, the recorded incidents of hate crimes seem to be on the rise and the ones against religious groups almost always place Jews at the top of the list.
Now, a spate of new books, big and small, recount the worldwide revival of anti-Semitism, including the so-called new anti-Semitism, which carries its own set of new myths.
This is what Tarek Fatah, a Canadian Muslim originally from Pakistan, discovered when he returned to his old homeland for a visit.
Pakistan is a country where hardly any Jews even live. But in Fatah's new book, The Jew is Not My Enemy: Unveiling the Myths that Fuel Muslim Anti-Semitism, he finds the country of his birth is a hotbed of conspiracy theories.
You've heard a few of them, no doubt, here in North America: That Jews, or the Mossad, the Israeli intelligence service, planned and executed 9/11 and warned the Jews who worked in the World Trade Centre not to go to work that day.
It doesn't seem to matter that Osama bin Laden and al-Qaeda gladly took the credit for this atrocity, the Jewish conspiracy myth seems to live on in many, receptive circles.
What Fatah found in Pakistan was that these ideas are mainstream, shared by all classes of society, the educated and uneducated alike.
He heard them again and again: Jews control the Western media and banks, the organs of information and economic power. Their handiwork is ubiquitous and evil, reaching out to pick the pockets of ordinary citizens and corrupt the body politic.
This notion of a treacherous Jewish influence has a long and grisly history, and it is this emphasis that marks anti-Semitism from other prejudices, according to the historian Robert S. Wistrich.
A professor at the Hebrew University in Jerusalem, Wistrich is arguably the world's leading historian of anti-Semitism. His most recent work is a vast thousand-page tome called A Lethal Obsession: Anti-Semitism from Antiquity to the Global Jihad.
It is chilling to read and relentless in its recounting of millennial Jew hatred throughout the ages.
Reading it, I frequently had to stop, upset and exhausted by the horrible things I had just taken in.
When, after interviewing Wistrich for an Ideas program, I asked him what it was like to write this book, he laughed gently and said he felt he had somehow been "chosen" to do so, knowing full well how loaded that word has been throughout Jewish history.
A chosen people
As Wistrich tells it, the idea of being a chosen people has been both a blessing and a notorious curse.
An ancient people, the Jews worshipped an all-powerful, morally demanding God who was something of a puzzle and who annoyed the more cosmopolitan Greeks and the imperial Romans of their day.
His Ideas interview can be heard online at CBCRadio.ca
These Greeks and Romans seemed to like their gods to be more like wayward humans, less severe and ethically scrupulous.
Throughout history, Jews were a separate people, marginalized and wary, but often skilled and successful at the tasks allotted them.
Still, even in the supposedly golden age of Muslim rule in Spain, the several centuries that began in 711 CE, the fate of Jews would hinge on whether their Muslim rulers were benign and required their services, or were fundamentalist and persecutory.
The relationship with Christians was often more difficult because underneath the many persecutions over the centuries was the idea that Jews were Christ killers, Satan's confederates.
These fantasies turned into the blood libel of the European Middle Ages when Jews were believed to kidnap Christian children, to use their blood in religious rituals.
This mythology of Jewish scheming carried over into our more secular age when Jews would be accused of all manner of connivance.
To the suspicious, they could be all things — capitalists and Communists, godless secularists as well as religious zealots.
In this way, Jews were sometimes depicted as the poison tip of modernity, polluting more rooted and ethnically pure communities, a favourite Nazi belief that has remarkable staying power.
The now infamous Protocols of the Elders of Zion, a forgery of Russia's Czarist police in the early 20th century, tells the tale of Jews who conspire to rule the world and who control the press, the banks and the lives of ordinary people.
Unfortunately, as Wistrich points out, the Protocols, as well as modern day stories about the blood libel, have been spread by the internet and turned into mainstream TV in the Middle East.
They are, in fact, central themes in a popular Egyptian TV production called A Horseman without a Horse. This, in one of the few Arab countries that has a peace treaty with Israel.
Reading Wistrich is both riveting and dispiriting. Is he too pessimistic, too relentless in his shaping of this lethal obsession?
For many, he might be. But setting that aside, he is clearly worried about the growing apocalyptic rhetoric in the region he inhabits, the repeated speeches by Iran's Mahmoud Ahmadinejad about wiping Israel off the map being only the most obvious example.
You can dismiss the Iranian president's remarks as the ravings of a lunatic or as those of a cunning politician with an ear for the apocalyptic beliefs of his audience.
But dismissing him that way can overlook what people like Wistrich see as history's long, lethal obsession with the Jewish presence, an obsession that we know can have disastrous consequences.