One of Europe’s leading Orthodox rabbis on Friday called on Jewish parents to ensure that their children are properly vaccinated with the Passover holiday approaching, as a measles outbreak among Orthodox Jewish communities in New York showed no signs of abating.

“It is well known how dangerous measles is and the need to ensure all vaccinations are up to date,” Chief Rabbi Pinchas Goldschmidt — the president of the Conference of European Rabbis — said in a statement.

Goldschmidt noted as the Jewish community prepared “for Pesach … they need to be aware that they may be exposing themselves and their families to the disease and to take the necessary precautions.”

The rabbi stressed that it was “also important to note that those traveling are advised to get vaccinations for their children from six months of age.”

He added: “This is even more pressing given the exposure many within the wider Jewish community have had to the disease.”

Goldschmidt’s statement came in the same week that New York City Mayor Bill de Blasio issued an emergency health order requiring measles vaccinations, with a $1,000 fine for those who decline. Sections of the Orthodox Jewish community in Brooklyn have refused to have their children vaccinated, on the grounds that doing so supposedly violates Jewish religious law.

The Center for Disease Control (CDC) has identified three ongoing measles outbreaks in the US in New York City and nearby Rockland County, as well as in jurisdictions in New Jersey, Michigan and California. The CDC said on its website that the outbreaks were “linked to travelers who brought measles back from other countries such as Israel, Ukraine, and the Philippines, where large measles outbreaks are occurring.” Public health officials previously declared measles to have been eliminated in the US in 2000.