HUNTINGTON BEACH, Calif. » Their children have been sent home from school. Their families are barred from birthday parties and neighborhood play dates. Online, people call them negligent and criminal. And as officials in 14 states grapple to contain a spreading measles outbreak that began near Disneyland, the parents at the heart of America’s anti-vaccine movement are being blamed for incubating an otherwise preventable public-health crisis.

Measles anxiety rippled thousands of miles beyond its center on Friday as officials scrambled to try to contain a wider spread of the highly contagious disease — which America declared vanquished 15 years ago, before a statistically significant number of parents started refusing to vaccinate their children.

In recent days, new measles cases popped up in Nebraska and Minnesota, and Marin County in California. Officials around the country reported rising numbers of patients who were seeking shots, as well as some pediatricians who were accepting nonvaccinated families but were debating changing their policies. The White House urged parents to listen to the science that supports inoculations.

In Arizona, health officials warned that 1,000 people could have been exposed to measles and urged anyone displaying symptoms to avoid this weekend’s Super Bowl events in the Phoenix area. In a small planned community where one family became ill after visiting Disneyland, store windows were lined with measles alerts, and a sign on the Pinal County office building warned: "Stop! Measles is in our county!" and asked people with symptoms to wear masks before entering. 

But in California, anti-vaccine parents whose children have endured bouts of whooping cough and chickenpox largely defended their choice to raise their children on natural foods, essential oils and no vaccinations.

"There is absolutely no reason to get the shot," said Crystal McDonald, whose 16-year-old daughter was one of 66 students sent home from Palm Desert High School for the next two weeks because they did not have full measles immunizations.

After researching the issue and reading information from a national anti-vaccine advocacy group, Ms. McDonald said she and her husband, a chiropractor, decided to raise their four children without vaccines. She said they ate well and had never been to the doctor, and she insisted that her daughter was healthier than many classmates. But when the school sent her home with a letter, Ms. McDonald’s daughter was so concerned about missing two weeks of advanced-placement classes that she suggested simply getting a measles inoculation.

"I said, ‘No, absolutely not,’ " Ms. McDonald said. "I said, ‘I’d rather you miss an entire semester than you get the shot.’ "

The anti-vaccine movement can largely be traced to a 1998 report in a medical journal that suggested a link to autism but was later proved fraudulent and retracted. Today, the waves of parents who shun vaccines include some who still believe in the link and some, like the Amish, who have religious objections to vaccines. Then there is a particular subculture of largely wealthy and well-educated families, many living in palmy enclaves around Los Angeles and San Francisco, who are trying to carve out "all-natural" lives for their children.

"Sometimes, I feel like we’re practicing in the 1950s," said Dr. Eric Ball, a pediatrician in southern Orange County, where some schools report that 50 to 60 percent of their kindergartners are not fully vaccinated and that 20 to 40 percent of parents have sought a personal beliefs exemption to vaccination requirements. "It’s very frustrating. It’s hard to see a kid suffer for something that’s entirely preventable."

Two of Dr. Ball’s patients are unvaccinated girls who became sick with the measles last week, though they had not been at Disneyland and it was unclear how they had been infected. Their father called the clinic to tell Dr. Ball and has been sending digital photographs of the girls, their faces stippled with red dots, to update him on how they are doing.

Dr. Ball said he spent many days trying to persuade parents to vaccinate their children. He tries to alleviate their concerns. He shows parents his own children’s vaccine records. But it has not worked, and lately, as worries and anger over this outbreak have spread, some families who support vaccines have said they do not want to be in the same waiting room as unvaccinated families. The clinic where Dr. Ball works has treated unvaccinated children for years, but its staff is meeting next week to discuss a ban.

"Our patients are really scared," Dr. Ball said. "Our nightmare would be for someone to show up at our door with the measles."

The Centers for Disease Control and Prevention reported that measles cases soared last year to 644, many more than in any other year in more than a decade. Since Jan. 1, the  C.D.C. has confirmed 84 measles cases in 14 states. California’s health department, which is updating a measles count more frequently, has reported 91 cases, with the biggest number, 27, here in Orange County.

The county’s vaccination rate for kindergartners is about 90 percent, slightly lower than the statewide rate, 90.4 percent. But rates in some pockets of the county, especially in the wealthier southern half, are sharply lower.

"There are different threads of concern out there" when it comes to vaccination, said Matt Zahn, the medical director for epidemiology at the Orange County Health Agency. "It becomes a game of Whack-a-Mole": As soon as you get rid of one issue, there’s another."

The people most at risk of becoming seriously ill are babies too young to be vaccinated and the immunologically frail; measles can transform into something much worse, like encephalitis, and can be deadly. Among the fully vaccinated, the chances of contracting measles are small but do exist; the C.D.C. says the vaccine is more than 95 percent effective. 

On Friday, all unvaccinated students who had been sent home from Huntington Beach High School after a possible measles exposure were allowed to return to school. But in Riverside County, officials reporting a probable case of a school employee with the measles ordered 40 students without vaccinations to stay home.

Similar scares are playing out far from Disneyland. In Kearny, Ariz., a small rural community with an economy tied to a nearby copper mine, a single family’s Christmas vacation has upended the rhythms of daily life. The family visited Disneyland in December, and four of its unvaccinated members came back with measles; a fifth person in Kearny also contracted the disease.

Now, many businesses in town — the grocery store, the post office, and more — have measles alerts in the windows featuring a blond boy with a rash all over his face. Several signs say that someone with measles was in the store at a specific time last week and advise others who were there at the same time to be alert to symptoms.

Some parents in Kearny are sympathetic to the family that did not vaccinate children.

"I strongly believe in getting children the vaccines they need to protect them from any childhood disease out there, but that is my opinion," said Tiffany Magee, a mother of three. "I also strongly believe other parents have the right to choose not to get their children vaccinated due to religion or health reasons."

Kearny school officials sent a letter home to all parents, urging calm, noting that, other than the children in the affected family, all other students in the district had been vaccinated. But it also advised parents to keep an eye out for symptoms. The measles outbreak has dominated talk in town and in two Facebook groups that discuss Kearny goings-on, and it has altered the way some people in town think about vaccines. 

Missy Foster, 43, said she had not vaccinated her daughter, Tully, who is now 18 months old, against measles because of concern that the M.M.R. vaccine — which stands for measles, mumps and rubella, or German measles — might be associated with autism.

"It’s the worst shot," she said, with tears in her eyes. "Do you want to wake up one morning and the light is gone from her eyes with autism or something?"

But as soon as Ms. Foster heard about the measles outbreak, she called her pediatrician and scheduled the vaccine, still with trepidation about possible side effects but with greater worries about measles. Now she is planning to stay home, leaving only to go to church, until the vaccine fully takes effect. 

"We didn’t think this would explode again, but it did," Ms. Foster said. "I want her to be protected." 

And Norm Warren, the manager of the supermarket in Kearny, Gordon’s IGA, has changed his thinking toward those who do not vaccinate their children. 

"Before, I thought, ‘If you think your child will become autistic, fine.’ But now they’re pushing their beliefs on everybody, and I feel differently," he said. "How many lives have been saved by vaccination?" 

Members of the anti-vaccine movement said the public backlash had terrified many parents. "People are now afraid they’re going to be jailed," said Barbara Loe Fisher, the president of the National Vaccine Information Center, a clearinghouse for resisters. "I can’t believe what I’m seeing. It’s gotten so out of hand, and it’s gotten so vicious."

In San Geronimo, Calif., a mostly rural community of rolling hills and oak trees about 30 miles north of San Francisco, 40 percent of the students walking into Lagunitas Elementary School have not been inoculated against measles, according to the school’s figures. Twenty-five percent have not been vaccinated for polio. In all, the state says that 58 percent of Lagunitas kindergartners do not have up-to-date vaccine records.

"A lot of people here have personal beliefs that are faith based," said John Carroll, the school superintendent, who sent a letter home to parents last week encouraging them to vaccinate their children. The faith, Mr. Carroll said, is not so much religious as it is a belief that "they raise their children in a natural, organic environment" and are suspicious of pharmaceutical companies and big business.

Some parents forgo shots altogether. Others split vaccine doses or stretch out their timeline, worried about somehow overwhelming their children’s immune system. Kelly McMenimen, a Lagunitas parent, said she "meditated on it a lot" before deciding not to vaccinate her son Tobias, 8, against even "deadly or deforming diseases." She said she did not want "so many toxins" entering the slender body of a bright-eyed boy who loves math and geography.

Tobias has endured chickenpox and whooping cough, though Ms. McMenimen said the latter seemed more like a common cold. She considered a tetanus shot after he cut himself on a wire fence but decided against it: "He has such a strong immune system."

As Ciel Lorenzen, a massage therapist, picked up her children, Rio, 10, and Athena, 7, at Lagunitas Elementary, she defended her choice to vaccinate neither of them, even as health and school officials urged a different course.

"It’s good to explore alternatives rather than go with the panic of everyone around you," she said. "Vaccines don’t feel right for me and my family."

Jack Healy reported from Huntington Beach, and Michael Paulson from Kearny, Ariz. Reporting was contributed by Patricia Leigh Brown in New Haven; Denise Grady in New York; Carol Pogash in Marin County, Calif., and Kristina Rebelo in Orange County, Calif.

© 2015 The New York Times Company