Berlin - When Judith G. helped out at a refugee center near Frankfurt last October and identified herself as Jewish, she was spat on and insulted.
German Jews say the case of Judith G., a 33-year-old optician who asked not to be fully named, isn't isolated and underlines concerns many have about the record arrivals of asylum seekers, largely from Muslim countries in the Middle East.
Official figures show German-born far-right supporters commit the vast majority of anti-Semitic crimes in the country, and Muslim leaders say nearly all asylum seekers - who can be targets of hate crime themselves - are trying to escape conflict, not stir it up.
Nevertheless, Jews across Germany are hiding their identity when volunteering at refugee shelters for fear of reprisals, adding another layer of complexity to a social, economic and logistical challenge that is stretching the fabric of German society.
"Among the refugees, there are a great many people who grew up with hostility towards Israel and conflate these prejudices with hatred towards Jews in general," Josef Schuster, president of the Central Council of Jews, told Reuters in an interview conducted in October.
Chancellor Angela Merkel stressed last week that anti-Semitic attitudes among some young people arriving from countries where "hatred towards Israel and Jews is commonplace" needed to be dealt with.
The safety of Jewish communities is particularly sensitive in Germany due to the murder of over 6 million Jews by Hitler's Third Reich, which is marked on Wednesday by the international Holocaust Memorial Day. Today, the German Jewish community numbers around 100,500.
According to a 2013 study by the EU Agency for Fundamental Rights, 64 percent of German Jews avoid the public display of symbols that would identify them as Jewish. It also found that only 28 percent of them report antisemitic incidents.
Such incidents, as recorded by the Interior Ministry, dropped in 2015 but Jews still remember chants by young Muslims proclaiming "Jews to the gas" on German streets in protests against the 2014 Israeli-Palestinian Gaza War.
Concerns rose earlier this year when two suspected asylum seekers from Syria and Afghanistan attacked and robbed a man wearing a skullcap on the northern island of Fehmarn, a crime the local prosecutor treats as antisemitic.
"We don't approach the issue of refugees with negative expectations in general," said Walter Blender, head of the Jewish community in Bad Segeberg, a town on the mainland about 100 km (60 miles) from Fehmarn. "But we are very worried and skeptical, and anecdotal evidence so far showed that we have reason to be scared."
Preliminary Interior Ministry figures show that far-right supporters were responsible for well over 90 percent of the antisemitic crimes recorded last year up to the end of November. People with a foreign background were blamed for little more than four percent, although this category does not reveal their country of origin or immigration status.