The small Pacific island nation of Samoa has closed schools and is restricting travel ahead of the holiday season as the death toll from a measles outbreak tops 50 in the latest flare-up of a global epidemic of the virus.

The vast majority of the dead are children under four years old, according to a government update.

The highly infectious disease has been crossing the globe, recently finding a susceptible population in Samoa, where vaccine coverage was only about 31 per cent when measles took hold, according to the World Health Organization (WHO).

In just over two weeks, the official death toll has jumped more than tenfold to 53 on Monday, the Samoan government said. There are now more than 3,700 cases of measles recorded in the population of around 200,000.

Samoa declared a national emergency last month and mandated that everyone in the country get vaccinated.

"All our schools are closed, national exams have been postponed," Rev. Vavatau Taufao, general secretary of the Congregation Christian Church in Samoa, told Reuters.

"We are still having church services but if it gets worse we will have to stop church altogether — and it's almost Christmas."

Measles cases are rising worldwide, even in wealthy nations such as Canada and the United States, as parents shun immunization for philosophical or religious reasons, or fears — based on misinformation that has been debunked by doctors — that such vaccines could cause autism.

Other nations, through either poverty or poor planning, have let immunization levels slip, exposing their youngest members to a disease that aggressively attacks the immune system.

WHO warned in October of a devastating comeback in measles epidemics as the number of reported cases rose by 300 per cent in the first three months of this year.

Reported measles cases are the highest they've been in any year since 2006, WHO said.

After causing devastation in Congo, Madagascar and Ukraine, among others, measles cases started appearing en masse earlier this year in the New Zealand city of Auckland, a hub for travel to and from small Pacific islands.

Dr Helen Petousis-Harris, a vaccinologist at the University of Auckland, said there were pockets of the community where immunization rates had slipped, allowing the disease to take hold.

"It's about being a good global citizen really, in that we all have to do our bit," said Petousis-Harris.

"I don't think that the response here has been a shining example. Because first of all we were aware of the possibility or the potential for this and that's been the case for a long time."

Samoan authorities have blamed low coverage rates in Samoa in part on fears caused last year when two babies died after receiving vaccination shots, according to local media reports.

A view of Apia in July. Samoa declared a national emergency last month and mandated all 200,000 people living in the country get measles vaccinations. (Jonathan Barrett/Reuters)

The country's immunization program was also temporarily suspended. The deaths were later found to have been caused by medications that were wrongly mixed.

Samoa has been racing to administer vaccines to children since the state of emergency was declared on Nov. 20. Health authorities have vaccinated 58,150 people so far, the government said on Monday.

Infection rates and deaths are still, however, climbing quickly with five fatalities in the past 24 hours, according to government data, prompting emergency restrictions on public gatherings and travel leading up to Christmas.

New Zealand Prime Minister Jacinda Ardern told reporters the country is sending additional vaccines and dozens of medical professionals to Samoa to help with the outbreak.

The government in Tonga attributed a recent measles outbreak in the small Pacific island community to a squad of rugby players returning from New Zealand, although higher vaccination rates in Tonga — and in neighbouring Fiji — have helped stem the outbreak.