"The vast majority of the at-risk children and adults who were in contact with the first case stayed in isolation until the risk of infection was over. However, the non-immunised family members of the case have measles.
"The latest case had been asked to stay in isolation for two weeks but has become infected.
"Unfortunately the child attended an early childhood centre for some days last week. Children do not usually receive MMR [measles vaccine] until 15 months of age so we are particularly concerned for the younger infants who have been in contact with this case, who are also the most vulnerable to complications such as pneumonia if they get measles. Measles can be a very serious illness, with one in three sufferers experiencing complications such as ear infections, pneumonia, bronchitis or diarrhoea."
Dr Mills says that, while one in 10, on average, requires hospitalisation, admission rates in the Hamilton outbreak have been higher and she urged parents and caregivers not to take their children to places such as day care or school if they show any symptoms of measles.
Even children exposed to others with measles need to be isolated for two weeks, she said.
She said immunisation is the best protection from this potentially serious disease.
"Unfortunately there has been very low measles immunisation coverage in much of Northland until the last few years. This means that many children and young adults are susceptible to measles," she said.
"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 and protects our most vulnerable - infants and people who are immune-compromised, such as those on cancer treatment.
"Please double-check that your child is not at risk. There is a window of opportunity now, while cases are limited to one part of Northland, to 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."
Dr Mills said Northland's MMR vaccination rate stood at 88 per cent - compared to a national target of 95 per cent - but 10 years ago it was down to 60 to 70 per cent.
What is measles?
• Measles is a highly infectious viral disease that can be serious.
• It is spread from person to person through the air by breathing, sneezing or coughing.
• Just being in the same room as someone with measles can lead to infection if you are not immune.
Who is at risk of measles infection?
• People younger than 45 (born after January 1, 1969) who have not had two doses of the measles-mumps-rubella (MMR) vaccine
• Infants under the age of 15 months who have not received their first routine dose of MMR vaccine. They are susceptible and rely on everyone else to be immune so that measles does not spread to them.
• Children over 4 years old who have not received their second dose of MMR.
