"The risk of others being infected is low because meningococcal bacterium is only spread by very close contact, or many hours of contact with an infected person."
St John's director of community health services, Sarah Manley, said: "Our thoughts are with the family and friends of our youth cadet who tragically died on Saturday night, and we will continue to support our youth members and their families through this tragic time."
A Ministry of Justice spokeswoman said the teenager's death had been referred to a coroner.
Dr Denise Barnfather, of the Auckland Regional Public Health Service, told the Herald today that meningococcal disease had been confirmed as the cause of the teenager's death. The strain was not yet known. Samples had been sent to an ESR laboratory in Wellington for strain identification, which was expected to take a fortnight.
The boy attended Kerikeri High School in Northland.
Principal Elizabeth Forgie said she was at school today with colleagues preparing to contact students and staff.
"Our thoughts are with his family and his friends at this terrible time. We will be there to offer them all the support we can."
She added she had been advised by Northland District Health Board public health nurses that there was "no significant risk" of meningococcal disease to the wider school community.
Barnfather, a medical officer of health, said preventative antibiotic treatment had been given to nine close contacts of the teenager by last night, but she expected that number to rise.
The teenager was at a St John youth camp at Motutapu for people aged 8 to 18. The camp was scheduled to end today.
The public health service said it had not been notified of any further cases of meningococcal disease.
A manager of the Motutapu camp, Duncan Watson, said there had been no further cases there.
He said the 16-year-old's condition worsened after he was taken to hospital, developing the characteristic rash of meningococcal septicaemia.
"My understanding is [it appeared] between leaving the camp, and hospital; I don't know whether it was in the helicopter or hospital."
Northland District Health Board Medical Officer of Health Dr Simon Baker said it was "very tragic for the family of the young man who died, and for everyone at the camp".
"We acknowledge the young people, their families and the staff at the camp will also be feeling very upset and anxious."
Northland public health nurses had been talking to the family about who else might have been at risk in the previous seven days in which the young man was infectious. Those who were in close contact with the young man had been provided antibiotics.
"Meningococcal disease is a serious and sometimes fatal disease, and can be difficult to diagnose, so we are providing information to the young people and parents so they can be alert for symptoms," Baker said.
"It can look like the flu early on but quickly gets much worse. It is important to get early treatment."
Symptoms included some or all of the following: fever; headache; vomiting; feeling sleepy, confused and delirious; loss of consciousness; joint pains; aching muscles; stiff neck; dislike of bright lights; or rashes, purple or red spots, or bruises.
Other symptoms in babies and infants included being unsettled, floppy or irritable, refusing drinks and feeds, and becoming harder to wake.
Children who had previously received meningococcal vaccination could still get meningococcal disease because the vaccine did not protect against all types of meningococcal bacteria, Baker said.
"If you or anyone you know has these symptoms, don't wait."
People with concerns should phone Healthline on 0800 611 116 or visit a doctor.
In 2011 an emergency vaccination programme was conducted in Northland against meningococcal C strain disease because of an outbreak of that strain that began in the region during the winter.
The outbreak mainly affected children and youth. By the end of December 2011, nine cases of meningococcal C had been confirmed, with three deaths.
Free (state-funded) vaccination was available for people aged from 1 to 20. More than 32,000 children and youth - around 73 per cent of the region's population in that age group - received the single-shot vaccine injection in three months.
One of those to die in the 2011 outbreak was plumbing apprentice Ben Brown, 18.
Previously fit and healthy, he fell suddenly sick one evening after work in August 2011. He had a painful neck, was seen sitting in a daze, was off his food and began to shiver uncontrollably.
He was taken to an accident and medical clinic, which sent him home with a meningitis leaflet and a prescription for oral antibiotics for tonsillitis, and paracetamol.
He deteriorated and went by ambulance to hospital, where he spent several hours before improving and being discharged. The oral antibiotics are thought to have masked the seriousness of his condition.
The day after he first felt unwell, Ben suddenly worsened, was taken to a GP clinic, then hospital. He was critically ill. He was given intravenous antibiotics, a CT scan, lumbar puncture test and was admitted to the intensive care unit (ICU).
Ben deteriorated. He died on a Saturday afternoon in Whangārei Hospital, the third day after he became unwell.
The hospital implemented changes to address matters identified in a review of Ben's care.