The Northern Sydney Central Coast Health (NSCCH) public health unit was notified of two separate and unrelated cases of meningococcal disease in the northern Sydney area on Thursday.

The two new cases have brought it to a total of three people suffering from the potentially fatal disease in the Sydney region. A toddler, with the same disease, was taken to a western Sydney hospital on Wednesday, where he was treated with antibiotics.

In Wellington, New Zealand, four children have been diagnosed with the same fatal disease. Two of the children have been fully vaccinated and one has received partial vaccination. All were infected with the epidemic strain of the disease, which is specifically targeted by the MeNZB vaccine.

Two further cases of meningococcal disease have also been confirmed in the Wellington region, both in older adults. Earlier in July six other confirmed cases were reported. A total of 10 cases in the greater Wellington region have been reported so far.

Regional Public Health Medical Officer of Health Margot McLean said though the infections were disappointing, vaccine breakthrough cases can occur and no vaccine was 100 per cent effective.

Parents have been warned to be aware of the signs of the disease, which include high temperature, headache, nausea, vomiting, irritability, weakness, drowsiness, a stiff neck, a pin-point or blotchy purple rash, and a dislike of bright lights.