BERLIN — Swastikas daubed on a Jewish cemetery in France. An anti-Semitic political campaign by Hungary’s far-right government. Labour lawmakers in Britain quitting their party and citing ingrained anti-Semitism. A Belgian carnival float caricaturing Orthodox Jews sitting on bags of money.

And that was just the past few months.

The accumulated incidents in Europe and the United States have highlighted how an ancient prejudice is surging in the 21st century in both familiar and mutant ways, fusing ideologies that otherwise would have little overlap.

The spike is taking place in a context of rising global economic uncertainty, an emphasis on race and national identity, and a deepening polarization between the political left and right in Europe and the United States over the conflict between Israel and the Palestinians.

“There’s an ideological pattern that is common,” said Günther Jikeli, an expert on European anti-Semitism at Indiana University. “The world is seen as in a bad shape, and what hinders it becoming a better place are the Jews.”