‘Concerning increase’: Whooping cough cases on the rise

Monday, 10 June 2024

Cases of whooping cough have increased 'significantly' recently, prompting calls from officials to get immunised

Health officials are reporting a ‘significant’ and ‘concerning’ increase in cases of whooping cough in Aotearoa.

Already in the first five months of 2024 there have been more cases (144) than in all of 2023 (141).

Nearly a fifth of cases so far this year have needed to be hospitalised.

Already this year there have been more cases of potentially fatal whooping cough than in all of 2023.

Data from the Institute of Environmental Science and Research (ESR) shows between January 1 and June 1, there had been 144 confirmed, probable and suspected cases of whooping cough across Aotearoa — compared to 141 in 2023.

Cases are on the rise in New Zealand, prompting doctors and health officials to urge people to be vigilant for symptoms and to get immunised.

Here’s what you need to know.

What is whooping cough?

Whooping cough (also known as pertussis) is caused by a bacteria called Bordetella pertussis.

Young children (less than a year old) are particularly at risk of severe illness and hospitalisation with whooping cough.

It causes bouts of intense coughing and trouble breathing. Each bout may last for two or three minutes, and the cough can last three months — so it’s sometimes called the ‘hundred day cough’.

Whooping cough can cause serious illness and sometimes death in babies, young children and other adults.

It’s very infectious, and is passed from person-to-person by coughing and sneezing.

On average, each person passes the infection to 12 other people.

More than half of babies under 12-months-old who catch it need to go to hospital, and up to 1 in 50 of these babies die.

Whooping cough can lead to pneumonia, seizures, paralysis, permanent brain damage, deafness and blindness.

There were three pertussis deaths in Aotearoa in 2023.

What does it look like?

Paediatrician Dr Owen Sinclair says outbreaks of pertussis tend to occur every few years, meaning it’s ‘inevitable’ we will see transmission.

Māori paediatrician and National Immunisation Taskforce chair, Dr Owen Sinclair (Te Rarawa) said pertussis is “awful”, and can be “extremely distressing”.

It can take 7–10 days for symptoms to appear once infected. They’re usually mild at first, resembling a common cold – such as a runny nose, nasal congestion, red watery eyes, fever and cough.

As the bacteria reproduce, they make toxins that paralyse cells in the windpipe and lungs which clear the airway of mucus and debris.

After a week or two, symptoms worsen. Thick mucus accumulates in the airways, causing uncontrollable coughing.

Severe and prolonged coughing attacks can cause people to vomit, suffer extreme fatigue, and other complications like bruised or cracked ribs or broken blood vessels.

Sinclair said a child sick with whooping cough may stop breathing and go blue. You sit them up, put oxygen on, hold their hands above their heads and “then hope they breathe again”.

There’s no treatment for whooping cough.

Data reported by ESR show a number of young babies, aged under 6 months, have been hospitalised for pertussis already this year.

Antibiotics may be given if diagnosed early and can help lessen spread to others, but may not be if diagnosed in the later stages.

“Once you have it, there’s nothing you can do about it,” Sinclair said.

What are the numbers showing?

National Public Health Service public health medicine specialist - protection, Dr Emma Sherwood said it is responding to a “recent concerning increase” in the number of pertussis cases across the country.

To the week ending May 31, 26 people with whooping cough have been hospitalised (18%), she said.

ESR’s pertussis dashboard shows there were 73 confirmed, probable and suspect pertussis cases in the month of May alone. There were five cases in May 2023.

So far, cases this year have been spread across a range of ages - from infants to those aged 65 and older - and across multiple regions and ethnicities, Sherwood said.

“While ESR’s reporting thankfully shows no deaths from pertussis [this year], we are concerned that cases have increased significantly.”

Why are we seeing this now?

Whooping cough is not under control in Aotearoa, Health NZ says.

There are outbreaks every 3–5 years, which tend to affect thousands (mostly young children).

Sinclair said it’s too soon to know if this increase is the start of an outbreak, but that “we will have one, and this could be it”.

“It’s a real wake-up call.”

Babies are recommended to receive pertussis vaccines at 6 weeks, 3 months, and 5 months old. There are booster doses given at ages 4 and 11, and later in life.

Sherwood said though the latest increase in cases is consistent with lower immunisation rates and the onset of winter, the trend isn’t limited to New Zealand.

Other countries, including Australia, were also seeing increased pertussis notifications, she said.

What’s the advice?

The best protection for infants is for their mother to be vaccinated during pregnancy, followed by on-time immunisations for the infant at 6 weeks, 3 months and 5 months, the Immunisation Advisory Centre says.

Booster vaccines are also given at ages 4 and 11.

It’s important to be vaccinated during every pregnancy to provide protection for an unborn child, Sherwood said.

Vaccination in pregnancy protects a baby until they are old enough to have their first vaccine, and is most effective when given from 16 to 26 weeks’.

If tamariki have missed immunisations, they can catch-up for free.

National Immunisation Schedule vaccines are free for those under 18 ‒ including visitors to Aotearoa, regardless of their visa or citizenship status.

Sherwood said public health officials are “closely monitoring” the situation, and had sent alerts out encouraging practitioners to remain vigilant for signs of pertussis.

If you or your tamariki are very ill, are having breathing difficulties, have long periods of coughing that end in vomiting, or turn blue from coughing, call 111 and ask for an ambulance. Young pēpi under 2 months may stop breathing as a first sign of whooping cough.