The largest outbreak of measles in New York in decades has now spread from one Hudson Valley county to another.

The Orange County Department of Health confirmed an infant tested positive for measles after visiting Rockland County.

In Rockland County, health officials have confirmed 75 cases of measles, it what is the biggest outbreak in the Empire State in decades.

In early November, Hudson Valley Post reported 40 confirmed cases of measles. In alerts prior it was 33 confirmed cases and  11 confirmed cases.

Last month, it was reported an international traveler with measles visited multiple locations in Rockland and Westchester counties. Among the locations infected with measles was the Costco in Nanuet and Westchester Medical Center.

Health officials told many Rockland County schools to keep all unvaccinated or under-vaccinated students home from school until 21 days have passed from the last confirmed measles case.

Measles is a highly contagious respiratory disease caused by a virus that is spread by direct contact with nasal or throat secretions of infected people. People first develop a fever, then often a cough, runny nose and watery eyes, followed by an appearance of a rash. People are considered infectious four days before to four days after the appearance of the rash.

Symptoms include a fever, rash, cough, conjunctivitis or a runny nose. Symptoms usually appear 10-12 days after exposure but may appear as early as 7 days and as late as 21 days after exposure.