Northland's rate of meningococcus-related deaths has health authorities warning about a sharp rise in a new, particularly virulent strain of the killer disease.
Three people have died in Northland in recent months from W meningococcal disease (MenW) - half the entire deaths in New Zealand over the past year.
Northland has seen seven cases of the deadly MenW strain so far this year, four of them showing up in September and October. The region has also had three cases of the group B strain.
There was no connection between cases and the patients' ages varied.
The Ministry of Health said 24 MenW cases were reported nationwide to November 5, including the six deaths.
One of the three Northland deaths was 16-year-old Dion Hodder, from Kerikeri.
Dion became ill during a St John youth camp on Motutapu Island in the Hauraki Gulf and died in Auckland City Hospital several hours later, despite receiving urgent medical treatment.
The MenW strain affects all age groups, said the director of public health, Dr Caroline McElnay.
GPs and emergency departments nationwide have been asked to be vigilant about possible symptoms of meningococcal disease.
The ministry has warned all medical practices and departments about the rise in MenW cases and the need to give antibiotics without delay when the potentially fatal disease is suspected.
Meningococcal disease is a bacterial infection that causes meningitis (an infection of the membranes that cover the brain) and septicaemia (blood poisoning).
It can look like the flu early on, but quickly gets much worse and requires treatment as early as possible.
The ministry said the wider public should boost its awareness to ensure anyone with possible symptoms seeks swift medical attention. Quick action can save lives, McElnay said.
Symptoms include fever, headache, vomiting, sleepiness, confusion, delirium, loss of consciousness, joint and muscle pain, a stiff neck, sensitivity to light, rashes, purple or red spots, or bruises.
Northland medical officer of health Dr José M Ortega said atypical MenW symptoms included stomach pain.
"It can be difficult to diagnose because it can look like other illnesses. It spreads through close intimate contact with other people. Those who live and sleep in the same house as someone with meningococcal disease are most at risk," Ortega said.
"The key message is if your child or family member is sick take them to the doctor.''
Children who have had the meningococcal vaccination could still contract the disease because the vaccine does not protect against all types of meningococcal bacteria.
There were 12 MenW cases reported in 2017, with three deaths, and 112 cases of meningococcal disease in general. So far this year there have been 96 meningococcal disease cases.
• Meningitis is most commonly caused by meningococcal bacteria. Meningococcal meningitis can cause septicaemia (severe blood poisoning).
• It can be treated with antibiotics but early treatment is vital.
• Most cases occur during winter or spring. Symptoms are flu-like but rapidly get worse, and include fever, headache, vomiting, sleepiness, delirium, joint pain and muscle pain, a stiff neck, sensitivity to lights, rashes, spots or bruising.
• Meningitis can be caused by bacteria (bacterial meningococcus) and viruses (viral meningitis).
• It can be caused by a number of bacteria but most commonly from meningococcal bacteria.
• Meningococcal disease is fatal in 10-20 per cent of cases. Among survivors, up to 20 per cent are left with a serious disability such as loss of skin, fingers, toes or limbs, hearing loss, epilepsy, brain damage, kidney failure or, in the very young, developmental delay.
• Meningococcal bacteria are common and live naturally in the nose and throat. The bacteria are present in saliva and can be spread through kissing, sneezing, coughing, sharing drink bottles or cups, plates, utensils or food, toothbrushes and baby dummies.
• An estimated 15 per cent of New Zealanders carry the saliva without getting sick.
In others, the bacteria overcome the body's defences. Incubation time, from when the bacteria enter the bloodstream to symptoms showing, is between two and 10 days.