The Auckland Regional Public Health Service is investigating a possible death from meningitis.
It said the patient had shown similar symptoms to the disease, which include a fever, headache, vomiting, loss of consciousness, a stiff neck, joint and muscle aches, and rashes with purple or red spots or bruising.
The potentially fatal disease is caused by the spread of bacteria from contact with an infected person.
The service said it was working closely with family members and others who may have come into direct contact with the patient to prevent the disease from spreading.
There are about 28 cases of meningococcal disease in Auckland each year.