Vials of measles, mumps and rubella vaccine are displayed on a counter at a Walgreens Pharmacy in Mill Valley, California.

A county in New York City's northern suburbs declared a state of emergency Tuesday over a measles outbreak that has infected more than 150 people since last fall, 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 U.S. before.

Day said he was taking the action in hopes of reversing a recent uptick 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 centers, schools, restaurants and even houses of worship. Those in violation could be charged with a misdemeanor punishable by up to six months in jail.

But Day acknowledged that there will be no concerted enforcement effort and that the intent is not to arrest people but to emphasize the seriousness of the situation.

"There will not be law enforcement or deputy sheriffs asking for vaccination records. That is ridiculous," Day said. "However, parents will be held accountable if they're found to be in violation of this emergency declaration."

The county is experiencing New York state's longest measles outbreak since the disease was declared officially eliminated from the United States in 2000. Health officials say the best way to stop the disease's spread is a vaccination rate in the community of 92 to 95 percent. Day said only 72.9 percent of people under 18 have been vaccinated against measles in Rockland County, which has more than 300,000 residents.

Civil rights attorney Michael Sussman, who represents the parents of 44 unvaccinated children who were barred from a Waldorf School in the county, said he would discuss a possible challenge to the emergency declaration in a meeting with his clients Tuesday night.

"It's irrational," Sussman said. "You're punishing people who don't have the illness rather than quarantining people who are sick."

Sussman said a quarantine of measles patients and those close to them would quickly stop the disease's spread.

This month, a federal judge, citing the "unprecedented measles outbreak," denied the parents' request to let unvaccinated children return to the Waldorf School. The lawsuit said the county's order banning unvaccinated children from schools regardless of religious or medical exemptions violated their constitutional rights.

The outbreak began in the Rockland area when seven unvaccinated travelers diagnosed with measles entered the county last October. There have been 153 cases to date, Day said. In the early days of the outbreak, people were cooperating with health officials and getting children vaccinated, he said, but that has changed.

"Our health inspectors have been hung up on and told not to call again. They've been told, 'We're not discussing this, do not come back,' when visiting the homes of infected individuals as part of their investigations," Day said. "This type of response is unacceptable and frankly irresponsible."