Northland Medical Officer of Health Jonathan Jarman is worried that an outbreak of meningococcal disease in the region is showing no sign of abating.
Twelve cases and three deaths have been confirmed since July.
Dr Jarman says eight of the cases have been Type C meningoccus, which is relatively uncommon.
He says it is particularly disturbing that in three of those eight cases the patients died, when the mortality rate in usually about one in 20.
Dr Jarman says it is also of concern that the numbers of people with meningoccal disease are not dropping, as they normally would at this time of year.