Dr Shoemack did not want to confirm the gender of the adult or the person's age in the most recent case as he did not want to "inappropriately concern or inappropriately reassure'' people.
"Everyone in New Zealand needs to be aware of the illness.''
Efforts had been made to contact those who had been in close contact with the adult and antibiotics had been offered.
Dr Shoemack said he did not know how long the adult was in hospital.
He said the number of cases so far this year remained about the same as the past few years.
However, the numbers were not as great as during the height of the epidemic in 2001 when there were 101 cases in the Bay of Plenty and Lakes District Health Board areas.
There are about 100 cases in New Zealand each year now.
He said the symptoms of meningococcal disease included severe headaches, vomiting, nausea, stiff neck and people getting quite drowsy to the point where they are not easily roused.
Young children can become irritable.
Dr Shoemack said those with symptoms, or their family members, needed to make a judgment call based on the severity of their illness and the time of the day as to whether to go to their GP or the hospital.
The symptoms were similar to those suffering influenza but the main difference was that with meningococcal disease a person became very sick very quickly.
"Constant awareness of those symptoms is necessary.''
He said although the weather was becoming warmer it did not necessarily lower the risk of meningococcal disease.
"Meningococcal disease is more common in the colder months,'' he said.
"We can anticipate fewer cases but they still occur in the middle of summer.''
Northland District Health Board is spearheading a mass vaccination campaign aimed at immunising up to 38,000 people aged 1-20 in the region against meningococcal C.
Since July there have been seven cases of meningococcal disease caused by group C bacteria in Northland, including three deaths: an 82-year-old woman who died on September 22, a 1-year-old and an 18-year-old.
Dr Shoemack said the vaccine would not be offered in the Bay of Plenty or Lakes districts at this stage as there had been no cases of the C group in the past year.
