New York state is battling one of the worst measles outbreaks in two decades as the highly contagious disease hits Orthodox Jewish communities in Brooklyn and Rockland County.

Fifty-five confirmed cases of the virus have affected unvaccinated children in Borough Park, Bensonhurst, Midwood/Marine Park and Williamsburg since October, according to the city Department of Health.

The measles outbreak in Brooklyn began when a child was infected on a trip to Israel, which also is seeing a large spread of the disease.

“Since then, there have been additional children from Brooklyn who were unvaccinated and acquired measles while in Israel,” DOH said.

“Children who did not travel were also infected in Brooklyn or Rockland County.”

As of Tuesday, the statistics include 32 cases in Borough Park, 21 in Williamsburg and one each in Bensonhurst and Midwood/Marine Park. Borough Park saw two new cases last week, while Williamsburg had one new case.

There have been 112 confirmed cases in the rest of New York state.

One hundred and five of those cases have been in Rockland County, which also has a high Orthodox Jewish population, with the rest in Orange County, officials said.

Rockland also currently has four suspected cases, pending test results. Eighty percent of the cases involved people under age 18.

The troubling spike has prompt­ed Rockland and state health officials to recommend that parents have their children get the measles, mumps and rubella vaccine earlier than scheduled.

Typically, the first dose of the vaccine is administered at the age of 1 and again at 4.

“We changed it to get their first shot at 6 months old,” said Rockland County spokesman John Lyon. “The second shot you can get 28 days after the first shot. We’ve been recommending that people do it immediately.”

Children who are vaccinated on the expedited schedule will need to receive another MMR shot at 4, Lyon said.

With the help of the state Health Department, Rockland has doled out 11,000 MMR vaccinations since October.

“Anyone who has not received an MMR vaccine should go to the doctor and get one as soon as possible,” advised state Health Department spokesman Jonah Bruno.

Early symptoms of measles appear 10 to 12 days after exposure and include fever, cough, runny nose and red, watery eyes. Three to five days later, a rash of red spots begins to appear on the face and spread over the entire body.