An 18-year-old man is seriously ill after he is believed to have contracted meningococcal disease in Northland, the fourth suspected case in the region this month.
Northland District Health Board medical officer of health Claire Mills said there was understandable anxiety in Northland communities, where there have been six cases this year.
Public health staff had identified people who had been in close contact with the man and offered them advice and preventative treatment.
He was admitted to Whangarei Hospital's intensive care unit last night where he was in a serious condition.
"When considering the number of Northland cases and other cases across New Zealand, Northland is seeing a small increase in this disease compared to other years, but meningococcal disease is also more common at this time of year, and these cases appear to be isolated," Dr Mills said.