A 10-week-old baby would have died from whooping cough if the Olympic Games had not been on late-night television, his mother says.

This year, Jenah Ramsay had to resuscitate son Nixson on the same day he was discharged from Christchurch Hospital with the potentially deadly disease.

The outbreak started on the West Coast and has spread to most parts of the country.

Canterbury has seen 1075 pertussis, or whooping cough, cases since August last year.

Canterbury District Health Board medical officer of health Alistair Humphrey said whooping cough rates were "still tracking above average".

Nixson was admitted to hospital for nine days after his mother took him to the doctor with suspected whooping cough.

Ramsay said her son had received the first dose of the whooping cough vaccination at six weeks and was due for his next jab at 12 weeks.

"Jason [Nixson's father] had a bad cough that went on for a while and he went to the doctor and they told him he had a chest infection and didn't test him for whooping cough," she said.

"By that time it was too late, and I noticed Nixson was having problems breathing one day, so I took him straight to the doctor and then we were taken to hospital."

The baby spent nine days in the paediatric ward before he was discharged.

"We came home and that night I was up really late watching the rowing final at the Olympics and I heard him struggling to breathe," Ramsay said.

"I ran in and he just wasn't breathing and he was blue, so I gave him CPR.

"I honestly thought he was going to die. It was the most terrifying thing."

Ramsay phoned an ambulance and Nixson was readmitted to hospital for a further nine days.

"The whole experience was awful," she said.

"He was turning blue 10 or 15 times a day and I just didn't know what was going to happen. He was so small and it was really awful to see.

"If the Olympics hadn't have been on then I would have probably been asleep in bed and wouldn't have heard him and I don't think he would have made it."

Ramsay's 5-year-old daughter also contracted pertussis and the whole family took a course of antibiotics.

Nixson, who is now 5 months old, had "only just got over whooping cough".

"It really is the 100-day cough and he was so unlucky to get it during that time between his vaccinations," Ramsay said.

- © Fairfax NZ News