A child has died of meningococcal disease, and the number of cases nationally is up 40 percent from this time last year.
The Palmerston North child died recently but was only discovered to have meningitis after their death.
MidCentral District Health Board acting chief medical officer Jeff Brown said the young child was "a treasured member of the family".
Warnings about the disease have been circulated to parents through schools and preschools in the Horowhenua District, which falls under the MidCentral DHB.
Those in close contact with the child have been given antibiotics, but more details would not be released, Mr Brown said.
ESR data shows nationally there have been 78 confirmed cases of meningococcal disease from January to the end of July - up 40 percent on the 55 cases by the same time last year.
About half are the B strain, and about a quarter are the previously-rare W strain (MenW).
Last year a string of deaths in Northland were caused by MenW, leading to an emergency vaccination campaign.
Mr Brown said all strains of the disease could look like other winter bugs, but MenW appears to be even harder to spot.
"The worrying thing for paediatricians and those looking after children is that ... there's some suggestion it can be harder to pick up earlier, and you may get sicker in a hurry," he said.
"It seems ... the more common presentations, with a petechial non-blanching rash, stiff neck, headaches, not liking bright lights - those sorts of things seem to be less common in MenW. So it masquerades as other winter ills, and it seems that the cases of Meningococcal W are more serious."
Typically the meningococcal disease is most likely to seriously affect young children, teenagers and young adults - but MenW seems to also hit adults hard.
In July and August MidCentral recorded three cases of meningococcal disease - compared to four for the whole of last year.
The strain that infected the child was not able to be determined by tests. But for the other two cases, one was MenW and one MenB, so they were not were linked, Mr Brown said
It is important everyone learns the signs of meningococcal infection, and that sick children are carefully monitored. But one of the crucial messages for the community was to always return to seek help if a patient deteriorated after they were assessed, he said.
"If we saw you and assessed that you weren't sick enough to come into hospital or sick enough to be treated - that's at that time. It doesn't mean that in a few hours or a few days you should not come back. If things change, come back.
"That sort of vigilance, from parents and caregivers - we need to have that to be vigilant enough to be able to pick up these cases, but not have to build twice as many hospitals and not have everyone on antibiotics, which is not the answer."
Meningococcal disease is a bacteria and can develop into both meningitis, and septicaemia - both of which are potentially fatal.
Symptoms of meningococcal disease include: Headache, vomiting, fever, confusion, sleepiness, delirium, loss of consciousness, aching muscles, joint pain, stiffness of the neck, aversion to bright light, purple or red spots, rashes and bruises. Babies and infants can be unsettled, floppy or irritable, refuse food and drink and be difficult to wake.
Parents and caregivers should look out for symptoms even if their child has previously been vaccinated.
Anyone with concerns is encouraged to call Healthline on 0800 611 116 or visit a doctor as soon as possible.