WELLINGTON - New Zealand is asking travellers to make sure they are immunised for measles before travelling to its biggest city, Auckland, as the country faces its worst outbreak in over 22 years.

"If you're thinking of travelling into or out of Auckland, you should make sure you're vaccinated at least two weeks before you go," Associate Minister for Health Julie Anne Genter said in a statement this week.

"This includes children from 12 months old," she added.

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

In the US, more than 1,200 cases have been recorded across 30 states in the worst outbreak since 1992, while other countries like Britain and Germany also recorded higher number of cases this year.

In New Zealand, 849 cases of measles have been reported so far this year, making it New Zealand's worst measles epidemic since 1997.

Of these, 731 cases are in Auckland, and almost a third of those came in the last two weeks as the outbreak accelerated, state broadcaster Radio New Zealand reported. The spread of the disease outside Auckland has been limited.

Earlier this week, about 300 Manurewa High School students were sent home after 13 students contracted measles. The school has told anyone not immunised to stay at home until next Monday (Sept 2).

"New Zealand's measles outbreaks are reflective of what's happening internationally. There are significant outbreaks occurring worldwide and cases from these countries are coming into Aotearoa," said Ms Genter, using the official Maori name for New Zealand.

A teenage girl from New Zealand sick with measles visited Disneyland and other popular tourist stops across Southern California earlier this month, possibly infecting others, local government health officials there warned.

Prime Minister Jacinda Ardern urged anyone who had not been immunised against measles to get vaccinated.

"I'm worried about those who choose not to be vaccinated, it is the most important thing that we can do to prevent the spread of an outbreak like this, so again, we just encourage everyone to make sure that they are vaccinated," Ms Ardern was quoted saying by Radio New Zealand.