An 11-year-old visitor to Northland has been diagnosed with measles while a toddler who is a foreign tourist is suspected of carrying the disease.
The 14-month-old is from Australia and both were treated at the Bay of Islands Hospital in Kawakawa last weekend but neither were admitted.
One went to the Ngawha Springs Hot Pools while being infected.
The Northland DHB is either contacting or has contacted more than 49 people who have potentially been exposed to the disease.
Parahirahi Ngawha Waiariki Trust, which runs the pools, was not aware of the first measles case and the dozens who could have been potentially exposed when contacted yesterday.
Trust chairman Te Tuhi Robust said his members would seek more information from Northland DHB before deciding what measures could be put in place.
The Northland DHB is urging those who were at the pools between 7pm and 8pm on Easter Monday to contact its Public Health Unit on 0800600720.
"It was only a matter of time before we saw measles in Northland given our low immunisation rate and, with many families travelling over the school holidays, the risk of being exposed to measles is far greater," Northland DHB Medical Officer of Health Dr Virginia McLaughlin said.
She said the present immunisation rate in Northland of 86 per cent was incredibly frustrating for her as a public health practitioner, practising in a developed country such as New Zealand.
The number of confirmed measles cases in New Zealand so far this year is 82, with the majority of them in the Canterbury region.
Only people who were born before 1969 or have had two measles, mumps, rubella (MMR) vaccinations are considered fully protected.
An estimated 95 per cent of the population must be immunised to prevent recurrent outbreaks of measles.
"Given our immunisation rates are very low it may be time to start looking at compulsory immunisation."
However, the Northland DHB does not have the powers to make immunisation compulsory.
Dr McLaughlin said measles was one of the most infectious diseases and under-immunised people who came within two metres of an infected person, however briefly, have a 90 per cent chance of contracting it.
Northland's low immunisation rate, she said, meant the most vulnerable people such as babies, children too young to be immunised, and those with immunosuppressive disorders were being placed at unnecessary risk.
"If you are found to be a contact of a case of measles (and not immune) you will need to stay away from work, school or public places for up to 14 days, to help prevent putting other people at risk.
"Note that the Medical Officer of Health will be enforcing these exclusion periods, to ensure that our community is protected, so the best way to avoid this is to get up to date with your immunisations now," Dr McLaughlin said.
All New Zealanders are eligible for two free doses of MMR.
She said those aged between 29 and 50 years old would have had only one measles vaccination and were not considered immune.
People between 14 and 37 years old were most susceptible to contracting the disease, she said.
"People need to be very aware of the symptoms of measles which starts with a fever and cough and runny nose and sore red eyes and then after three or four days a rash appears on the face and then spreads to the body.
"You are contagious five days before to five days after rash onset – so in the early stages you may spread the infection without actually knowing you have measles."
Dr McLaughlin has advised people who have symptoms suggestive of measles to immediately seek medical advice and to avoid contact with young children.
They should call ahead to alert their doctor about the possibility of measles before visiting to allow GPs to make arrangements to assess them safely and without infecting others, she said.
* A highly infectious viral illness spread by contact with respiratory secretions through coughing and sneezing
* Symptoms include a respiratory type of illness with dry cough, runny nose, headache, temperature over 38.5C
* A red blotchy rash starts on day 4 or 5 of the illness, usually on the face and moves to the chest and arms.
* People are infectious from five days before the onset of the rash to five days after the rash starts.
* Infected pesons should stay in isolation – staying home from school or work – during this time.
* People are considered immune if they have received two doses of MMR vaccine, have had a measles illness previously, or were born before 1969.