Wellington, June 21 NZPA - Health authorities are warning parents to make sure that babies' whooping cough immunisations are up to date as the number of cases of the potentially deadly illness surges.

The Herald on Sunday said 92 people had been diagnosed with whooping cough -- often known as the 100-day cough -- in Auckland this year compared with 57 for the whole of last year.

Cases had also surged in Waikato and Canterbury, the latter recording 145 so far compared with 15 for the first six months of last year.

Auckland Regional Public Health Service clinical director Dr Julia Peters said parents must ensure babies' immunisations were up to date, and take them to the doctor if they had coughing fits which ended with a "whoop" noise.

"They may be perfectly fine between fits but when they have one it's nasty," she told the newspaper.

"They may struggle to breathe, vomit or even turn blue."