A measles outbreak across the North Island has so far been contained to only 10 people who contracted the disease following a hip-hop event in Sydney.
Bay of Plenty and Lakes District medical officer Neil de Wet said there had been no more cases reported overnight outside of the nine in Taupo and Turangi and one confirmed case in Auckland.
People who have been in contact with those who have the disease that have since headed to Wellington are also being checked and told to stay in isolation until they receive the all-clear.
Public health officials have warned people who attended the World Supremacy Battlegrounds in early December - and anyone else who has come into contact with them - to look out for symptoms of the infectious disease.
Four of those who have contracted the disease were at the event, and the others came into contact with them.
Nobody has yet been admitted to hospital but all those infected - ranging in age from five to 28 - have been isolated.
Dr de Wet said anyone over the age of 45 is assumed to be immune because measles was common before 1969 and it was likely they would have already been exposed.
"If you're not immunised and under 45 then you should get up to date and if you're unsure then go to your GP and check,'' he said.
"The main thing is to try and prevent the spread.''
If anyone has been in contact with the dance groups that went to Sydney they should call a doctor and take precautions so they don't affect other people that could be in the waiting room.
"From a public health perspective this is a very infectious illness and although the vast majority of people will make a full recovery about 30 per cent get complications including things like pneumonia, ear infections and diarrhoea.''
Dr de Wet said about 1 in 1000 people die of measles in New Zealand but with any outbreak the number of people potentially exposed increases and that means the rates of complications and mortality also increase.
Following the hip-hop event New South Wales health authorities have also confirmed three measles cases and issued a public warning on Tuesday after an Adelaide competitor became ill.
Public health staff in New Zealand are interviewing people who attended the event, checking whether they were immunised or infected, and have been getting in touch with anyone with whom infected patients have been in contact.
Auckland's last major measles outbreak, in 2011, resulted in nearly 500 cases and 80 hospital admissions, and this is the city's first case since June 2012.
Ministry of Health acting deputy director of public health Harriette Carr said any outbreak was significant because it was New Zealand's goal to become measles-free.
However, the latest outbreak was not yet an epidemic.
"It's highly infectious, and the problem with measles is that people are infectious for five days before they get the symptoms . . . people are giving it to other people before they know they've got it."
Identifying and isolating people until measles could be ruled out was important to stop it spreading, as the number of cases could multiply quickly, she said.
There was a perception that measles was a mild disease, but she warned it could be very serious for those who were vulnerable, such as babies and the elderly.
New Zealanders born before 1969 are likely to have been exposed to the disease as children, and are considered immune.
However, Dr Carr said those born after 1969 and before big pushes to improve measles immunisation rates were at risk.
"It's very important if people have symptoms of measles that they seek medical advice.
"Because measles can be easily spread, however, it's also important that people contact the Healthline 0800 number or ring their doctor first, so that their symptoms can be initially assessed without risk of infecting others in a GP waiting room or hospital emergency department."
She said the latest outbreak was a reminder that the most effective protection against measles was immunisation.
"I think the message is, if you haven't been immunised, it's a good new year's resolution."
MEASLES: WHAT IS IT?
An easily spread, severe viral infection of the respiratory system, passed on by coughing and sneezing.
Symptoms include high temperature, sore eyes and runny nose; small white spots developing inside the mouth; harsh, dry cough; reduced appetite, aches and pains; diarrhoea and vomiting; red blotchy rash developing three or four days after initial symptoms, usually starting on the head and neck.
Children are usually miserable for about a week before recovering.
In some cases measles can cause fits, encephalitis (brain inflammation), hepatitis (liver infection) and pneumonia (lung infection). It can become serious in pregnant women, people with weakened immune systems, and babies.
Anyone with any of the above symptoms should contact their family doctor or call Healthline on 0800 611 116 as soon as possible.
Call before visiting the doctor because measles is easily passed on. Stay away from work, or public places, and from family members if they are not fully immunised.
- © Fairfax NZ News
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