A case of measles has been confirmed in Northland this week.
Northland District Health Board has reported an unimmunised child came in contact with children from the Waikato and contracted the disease.
Northland DHB medical officer of health Clair Mills said a family with measles travelled from the Waikato to Northland, against medical advice.
"Measles is highly-infectious and if children are not immunised there is a very high chance they will get sick if exposed to someone with measles."
Dr Mills advised Northlanders to ensure their families are protected from measles.
"We are following up over 120 children and adults who were in contact with this case, forty per cent of whom are not fully immunised. Sadly this is to be expected, given very low immunisation coverage in much of Northland over the last 30 years."
"Measles can be a very serious illness, with one in three sufferers experiencing complications such as ear infections, pneumonia, bronchitis or diarrhoea," Dr Mills said.
"While one in 10, on average, requires hospitalisation, admission rates in the Hamilton outbreak have been higher."
She reiterated that immunisation was the best protection from this potentially serious disease.
"This is an avoidable disease where there is an effective vaccine. Immunisation protects, not only the individual, but also stops the spread of this disease within our communities.
"Please double-check that your child is not at risk and catch up on any missed vaccinations. Vaccination is a much better option than having a very sick child at home for a couple of weeks."
This year, 265 confirmed measles cases have been reported from the Auckland region, Waikato, Bay of Plenty, Lakes, Hawkes Bay, Taranaki and Wellington, with more than 100 cases from the recent outbreak in a high school in Hamilton.