The government of American Samoa has declared that the US territory has an outbreak of measles, a move that will lead to the closure of public schools and a ban on gatherings in parks.
In its announcement on Friday the government said the territory had nine cases of measles. Five of those infected had been travelling outside the territory.
As for the other four people who tested positive for measles, "we're suspecting that is local transmission - meaning that it's most likely, that some of these travellers did transmit the measles virus to them, causing them to be sick," Health Department Epidemiologist Dr Aifili John Tufa said.
Samples from those infected were sent to Hawaii for testing and the results came back on Thursday, resulting in the move to let the public know that "we are currently in the state of emergency" and a "measles outbreak", Dr Tufa said.
In the neighbouring independent nation of Samoa, 65 people have died, mostly children and more than 4500 were infected since a measles outbreak started in October, health officials said.
Almost 90 per cent of eligible Samoans have now been vaccinated with a two-day curfew lifted on Saturday.
Samoa declared a state of emergency and complete shutdown of government and business operations while vaccination teams searched for residents susceptible to the disease, health officials said.
About 34,000 people were immunised over two days, officials said.
There were, however, 103 new cases of measles reported since Friday, Samoa's Health Ministry said in a statement.
American Samoa will get a measles vaccine shipment from the US Centers for Disease Control and Protection on Monday, Tufa said.
Data presented by health officials early this week during a cabinet meeting shows a 99.7 per cent vaccination rate for mumps, measles and rubella in the territory, officials said.
But Tufa said that more needs to be done to up the rate for the 1-5 year age group which is currently at 84.7 per cent.
"The number one way to stop the spread of measles is to immunise," he said.
The developments in American Samoa came after dozens of Hawaii health care workers returned to their homes across the state after voluntarily providing measles vaccinations to thousands of residents of the independent nation of Samoa, officials said.
A team of 76 health care workers and support staff went to Samoa for a two-day medical mission to ensure residents in the independent nation of Samoa were immunised from the highly contagious virus, the Honolulu Star-Advertiser reports.
"You have scores of people dying, and the society is paralysed," said Honolulu surgeon Paulus Tsai. "Basically life has come to a standstill for the island."