Measles cases in the U.S. are surging at the fastest pace in nearly two decades, fueled mostly by unvaccinated travelers sparking outbreaks from California to New York — and, now, in Ohio, where 13 members of an Amish community may have fallen ill.

The travelers are contracting the highly contagious virus in places like the Philippines — where a measles outbreak has sickened more than 20,000 people and killed at least 50 — and then infecting communities of unvaccinated children and adults back home.

"Current outbreaks of measles in the U.S. serve as a reminder that these diseases are only a plane ride away," CDC Director Dr. Tom Frieden said Thursday. "Borders can't stop measles, but vaccination can."

At least 129 measles cases from 13 states have been reported in the U.S. in 2014 so far, the highest number for the period since 1996, officials with the Centers for Disease Control and Prevention reported.

But those figures don’t count cases reported after April 18, including four unvaccinated Amish people who went to the Philippines to help with typhoon aid and returned to possibly infect nine others, according to Pam Palm, a spokeswoman for the Knox County, Ohio, Health Department. Test results are pending for victims who range in age from 2 to 48 in the community where vaccination is discouraged.

Health officials are concerned about the growing cases of measles nationwide, which are on track to outpace the 189 logged last year and the 220 cases reported in 2011.

"People think their decision only impacts them and they overlook the young babies who are affected and don’t have a choice."

In California, which is leading the surge, there have been at least 58 measles cases this year, nearly all of which have been imported by unvaccinated travelers, according to the CDC report. Those travelers spread the highly contagious infection to people at a church, on an airplane and at a school, the report said.

Most of the California cases were in people who were unvaccinated or had no vaccination documentation. Of the 25 who weren’t vaccinated, 19 had philosophical objections to the vaccine.

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Three of those cases were in kids too young to get the vaccine, a situation similar to current outbreaks in New York, where 26 cases have been identified, including at least four in babies younger than 12 months, health officials said.

That alarms Megan Campbell, 35, of San Diego, California, whose son contracted measles when he was 10 months old after sharing a waiting room with a sick child whose parents didn’t believe in vaccination.

“He breathed the same air in the waiting room for about 30 seconds,” Campbell said.

Her son was hospitalized and ran a 106-degree fever for weeks in 2008. Campbell said she’s still haunted by the illness that threatened his life, all because of another family’s choices.

“It is a very selfish perspective. People think their decision only impacts them and they overlook the young babies who are affected and don’t have a choice,” she said.

But recent research shows that pro-vaccination messages actually backfire and that growing numbers of parents are deferring or delaying vaccines because of concerns about possible side-effects on their own children.

Despite the rise in cases, some U.S. doctors might not recognize the signs and symptoms of measles, which was considered eradicated in the country in 2000, said Dr. Julia Shaklee Sammons, in an online commentary published Thursday in Annals of Internal Medicine.

Indeed, Campbell said doctors thought her son had Kawasaki disease, which also produces a rash. Others mistake measles for scarlet fever or Fifth disease, wrote Sammons, a professor of pediatrics at the Perelman School of Medicine at the University of Pennsylvania.

“It is crucial that providers become familiar with this deadly disease and apply the necessary control measures to contain it,” she wrote.

"It is crucial that providers become familiar with this deadly disease and apply the necessary control measures to contain it."

Before a measles vaccine was licensed in the U.S. in 1963, about 500,000 cases occurred nationwide each year, resulting in 48,000 hospitalizations and 500 deaths, the CDC says. Measles is highly contagious; about 90 percent of people who aren't immune will catch the disease if they're exposed.

Immunizations for measles and other childhood diseases provided through the national Vaccines for Children program have prevented more than 21 million hospitalizations and saved 732,000 lives since the program was implemented in 1994, the CDC said in a report Thursday. The VFC program was launched in direct response to a measles resurgence that caused more than 100 deaths.

More than 90 percent of U.S. parents choose to vaccinate their kids against measles and other childhood infections on schedule, but in certain parts of the country — particularly 20 states that allow philosophical exemptions to vaccination — opt-out rates for the are much higher, research shows.

Some states have tackled the problem by making it harder to obtain philosophical exemptions. In California, a law passed in 2012 requires that parents visit a doctor to discuss the benefits of vaccination before they can file a personal belief exemption with the school.

But other health experts believe that simply adding hurdles isn’t the best way to solve the problem leading to outbreaks of measles and other vaccine-preventable diseases such as mumps and pertussis or whooping cough.

A new report Thursday from the American Academy of Arts and Sciences calls for new research into how, when and why parents make vaccination decisions and the best way to communicate with those who are hesitant.

A certain proportion of parents objects to vaccines and there’s probably no changing their minds, said Barry Bloom, an expert in infectious diseases from the Harvard School of Public Health who is co-chairing the effort. But if they want to reach parents in the middle — and stop the surge of public health consequences — doctors and researchers are going to have to do better.

“This concerns an awful lot of people who genuinely want to do what’s best for their kids,” he said.