A rise in cases of whooping cough in Auckland has health officials worried that parents are not immunising their children.
The Auckland Regional Public Health Service says the last surge in cases of whooping cough was four years ago.
Its medical officer of health, Cathy Pikholz, says the number of notified cases to the health service has more than doubled in the past six weeks compared with the same period a year ago.
Sixteen cases were notified from 1 December to 13 January, compared with six notified over the same period in 2007 to 2008.
Dr Pikholz says babies under the age of one are at most risk of serious complications from whooping cough.