Medical Officer of Health Richard Hoskins said there had been 15 probable or confirmed cases of mumps in Waikato in the first six months of this year.

Waikato parents are being urged to check their children's vaccination records after a surge in the number of mumps cases.

Fifteen probable or confirmed cases of mumps have been recorded in the first six months of 2017.

Until this year, there were no mumps cases recorded in Waikato since 2012.

And it's not just the Waikato noticing an increase - nationally, an unusually high number of cases were reported from September 2016 to early 2017.

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Those 25 cases prompted the Ministry of Health to warn in February of "an increased risk of further outbreaks".

On Monday, the Auckland Regional Public Health Services said it was concerned not enough people were immunised in the face of the mumps outbreak.

Medical Officer of Health Richard Hoskins expects "some leakage of cases" from Auckland to Waikato.

"Two of our cases have been linked back to probable exposure in Auckland but the other 13 we haven't been able to link to any previous case or overseas travel," Hoskins said.

"They are sporadic cases. Fifteen cases is out of the ordinary and indicates that we are part of an outbreak."

There have been 142 mumps cases in Auckland, compared with 35 last year.

And the whole country's tally of reported mumps cases around the country is well up on this time in 2016, according to monthly public health reports.

The first five months of 2017 brought 147 cases of mumps - including those deemed probable or under investigation, the ESR reports say.

There were just two over the same period in 2016.

Hoskins advises parents to check their children's measles mumps and rubella (MMR) vaccinations are up to date.

Mumps is spread through coughing and sneezing and through direct contact with infected saliva.

The primary sign of mumps is swollen salivary glands. Other symptoms include headache, muscle aches, fever, pain in the jaw, and fatigue.

Mumps is an acute viral illness. Immunity is created through past exposure to the virus or effective vaccination.

People can ask their GP to check their vaccination record.

The MMR vaccine is given in two doses, normally at 15 months and 4 years of age.

"If someone is uncertain and there is no documentation, then have a catch-up," Hoskins said.

"It doesn't hurt to have an extra one even if you've already had two, but you're certainly more at risk if you haven't had the vaccine."

Mumps is difficult to contain and can spread relatively easily among young people in enclosed communities such as hostels, barracks or communal living-type situations, Hoskins said.

Eliminating diseases such as mumps and measles requires 95 per cent of the population to be immunised. Across New Zealand, about 91.5 per cent of five-year-olds have had their two doses of the MMR vaccine.

"This is really good but it's lower than it needs to be. Added to this is the issue that with the mumps vaccine, the immunity wanes at a higher rate than it does for the measles or rubella component for that particular vaccine. About 10 per cent of people won't be immune 10 years after receiving the vaccine."

Hoskins said it's important people practice good cough and sneeze etiquette and wash their hands after blowing their nose.

"If you have an upper respiratory infection, you've got to realise that coughing and sneezing is the virus' way of spreading itself because that puts the virus out into the air. Rather than following the advice of the advertising industry, don't soldier on because coughing and sneezing helps spread the virus. Do you school friends and work mates a favour and keep yourself at home until your symptoms go away."