Samoa has declared a state of emergency this weekend, closing all schools and cracking down on public gatherings after several deaths linked to a measles outbreak that has spread across the Pacific islands.

The island state of just 200,000, south of the equator and halfway between Hawaii and New Zealand, declared a measles epidemic late in October after the first deaths were reported.

Since then, at least six deaths – mostly infants under the age of two – have been linked to the outbreak, the health ministry said in a statement late last week. Of the 716 suspected cases of measles, 40 per cent required hospitalisation.

As of the weekend, vaccination “for members of the public who have not yet received a vaccination injection, is now a mandatory legal requirement”, the government said in a statement.

Only about two-thirds of the population has been immunised, according to the health ministry.

“The way it is going now and the poor (immunisation) coverage, we are anticipating the worst to come,” Samoa’s Director General of Health Leausa Take Naseri was cited in the health ministry statement as saying.

He added that the children who died had not been vaccinated.

The complex measles infection cycle. Illustration: American Society for Microbiology

New Zealand Foreign Minister Winston Peters said on Friday his country would send 3000 vaccines and 12 nurses to Samoa to assist with the outbreak.

“Measles is highly contagious, and the outbreak has taken lives in Samoa,” Peters said in a statement. “It is in everybody’s interests that we work together to stop its spread.”

Measles cases are rising globally, including in wealthy nations such as the United States and Germany, where some parents shun immunisation mostly for philosophical or religious reasons, or concerns, debunked by medical science, that such vaccines could cause autism.

Repeated studies have also found the initial infection can compromise the immune system and spawn further medical issues in later life.

In Tonga, about 900km from Samoa, the ministry of health last week said an outbreak of measles in the country occurred following the return of a squad of Tongan rugby players from New Zealand.

Since then, 251 cases of confirmed or suspected measles have been identified, the ministry said in the statement.

American Samoa, a US territory neighbouring Samoa, declared a public health emergency on Thursday following the measles outbreak in Samoa and Tonga, according to New Zealand media.

According to Samoa’s Naseri about 90 per cent of the population in Tonga and American Samoa has been immunised and neither of these countries have reported any measles-related deaths.

-AAP