Albany: A county in New York City's northern suburbs declared a state of emergency on Tuesday over a measles outbreak that has infected more than 150 people since last autumn, hoping a ban against unvaccinated children in public places wakes their parents to the seriousness of the problem.

"It's an attention grab, there's no question about it," Rockland County executive Ed Day said at a news conference, noting that he didn't believe such a drastic step has ever been tried in the US before.

Day said he was taking the action in hopes of reversing a recent rise in cases amid disturbing reports that health workers were encountering resistance when investigating cases. Rockland's outbreak has most heavily affected Orthodox Jewish communities, in which vaccination rates tend to be lower.

Under the declaration, which lasts for at least 30 days, anyone under 18 who is not vaccinated against measles is barred from public gathering places, including shopping malls, civic centres, schools, restaurants and even houses of worship. Those in violation could be charged with a misdemeanour punishable by up to six months in jail.