A WHOOPING cough outbreak on the North Coast is being blamed on low immunisation rates in the region.

North Coast Area Health Service acting director of public health, Greg Bell, said there had been three times as many cases as for the same period last year.

"The ones in danger are the little ones under 12 months. Most times when they have complications they are not able to breathe," he said.

He said 27 of the 50 cases reported state-wide were in this region, with many of those in the Byron and Lismore local government areas.

"Up here we seem to get a little bit starting in the Mullumbimby and Byron areas in the six-to-nine year age group and it just keeps going from there," he said.

"In this area where people choose not to immunise we haven't got the benefit of the immunisation herd effect."

Cobbers Child Care Centre in Mullumbimby had first-hand experience of the problem two weeks ago when the sibling of one of the preschoolers was diagnosed with the disease.

The preschooler had to be removed from contact with other children and all parents notified.

Co-owner Sharon Wearne said none of the kids had been diagnosed with the disease and the responsible action of the parents coupled with notification worked well to protect the other children.

Ms Wearne said the child diagnosed with whooping cough was immunised against the disease, which highlighted that immunisation was not 100 per cent effective.

Whooping cough, or pertussis, is caused by infection of the throat and usually begins with cold-like symptoms.

When the cough develops it occurs in bouts and is followed by a deep gasp or whoop sound.

Sometimes people also vomit from the strain of coughing.

The most vulnerable are babies under six months who have not been immunised.

Children are immunised at two, four and six months.

The vaccine is not permanent and booster shots are needed at age four and 15, with many adults having little resistance.