Parents in Northland are being urged to immunise their children against whooping cough after a outbreak of cases across the region.
This year Northland District Health Board has recorded 47 cases of whooping cough, compared to 10 cases for the whole of last year.
Whooping cough starts like a flu, but after a few days bouts of coughing start.
The board's medical officer of health, Jonathan Jarman, says the coughing is what does the most damage to babies.
He says young children often stop breathing and turn blue after coughing.
The coughing is worse at night and can last for many weeks.
Dr Jarman says immunisation is the best protection against the disease.