A rare diphtheria outbreak is spreading across the ditch, but are Kiwis at risk of the potentially life-threatening disease in New Zealand?

University of Otago professor of public health Michael Baker told the Herald that although the risk to New Zealand remains low, it has risen, given the number of cases in Australia.

ABC reported that the number currently sits at 242 cases this year and one confirmed death. Meanwhile, New Zealand has not had a case of respiratory diphtheria since 1998, Baker said.

He said the disease has become virtually banished across most of the world due to immunisation, so it was “unusual” to see an outbreak like this.

“This is by far the largest outbreak in Australia for decades,” Baker said.

What is diphtheria?

Health NZ Te Whatu Ora said diphtheria is highly contagious and spreads easily via coughs and sneezes, or through close contact with someone who is infected.

The bacteria can also spread through contaminated objects or food.

Health NZ said diphtheria can cause throat infections that can lead to breathing difficulties, and can cause skin infections.

Australian outbreak and the risk to NZ

Australia is currently grappling with an ongoing outbreak of the disease.

Northern Territory (NT) Health first declared an outbreak of diphtheria in March, for the first time since the 1990s, ABC reported.

The disease has since spread to Western Australia, South Australia and Queensland.

The Australian Centre for Disease Control (CDC) has recorded at least 242 cases of diphtheria throughout Australia this year, with 146 cases in the NT.

Australian Federal Health Minister Mark Butler said the source of the outbreak should be investigated.

“Having an outbreak that is so big, compared to the historical position of a disease most developed countries have consigned to the dustbin of history, does mean we have to examine what went wrong here,” Butler said.

University of Otago professor of public health Michael Baker.

Baker said generally the countries Kiwis visit most frequently have had good control of diphtheria for decades, but this outbreak “is a change in the normal situation”.

He said at this stage the Australian outbreak was still very localised and was in more rural Aboriginal populations, particularly in the Northern Territory and Western Australia.

“There is an increased risk of importing it into New Zealand. It’s still small, and of course it’s very much related to where New Zealanders go when they’re in Australia,” Baker said.

Baker said the outbreak was an important reminder for people to check their vaccination status for diphtheria.

“If we haven’t had a full course of vaccines as a child, or boosters as an adult, then we need to go and get our diphtheria vaccine topped up,” he said.

The best protection against diphtheria is immunisation. Photo / Getty Images

New Zealand’s Director of Public Health Dr Corina Grey said the Ministry of Health is in regular contact with Australian health authorities about potential health threats, including diphtheria.

“While some Australian states are experiencing a diphtheria outbreak, the risk to New Zealand is considered low,” Grey said.

In response to the outbreak in Australia, Health New Zealand has issued a public health advisory to healthcare professionals and an advisory to border agencies.

“The advisories are asking health professionals and border officials to be alert for diphtheria in returning travellers from Australia and areas where the disease is endemic, including Asia and the South Pacific,” she said.

What are the symptoms?

Grey said diphtheria often begins with mild, cold-like symptoms but can quickly become severe.

Common symptoms can include:

• Thick, grey-white coating at the back of the throat which can block breathing and cause death;
• Fever;
• Sore throat;
• Headache;
• Difficulty breathing;
• Difficulty swallowing;
• Bad breath;
• Sleepiness;
• Throat and neck swelling caused by swollen glands known as a ‘bull neck’;
• Bark-like cough.

Health NZ said diphtheria can cause pus-filled blisters on the skin and large ulcers surrounded by red, sore-looking skin.

While some cases may be mild, diphtheria bacteria can make dangerous toxins that cause severe and life-threatening complications.

Health NZ said 5 to 10% of people with diphtheria throat symptoms die, and up to 20% of people aged under 5 or over 40 die.

The best protection against diphtheria is immunisation.

Grey said the best protection against diphtheria was immunisation.

“In New Zealand, the vaccines that protect against diphtheria are given as part of the childhood immunisation programme,” she said.

Grey said our child immunisation rates are improving, with 82.9% of children fully immunised at 24 months as of December 31 last year.

Baker said New Zealand’s vaccination coverage was lower than Australia’s.

“On paper, we are actually more vulnerable to diphtheria transmitting in New Zealand. So I think it is important that New Zealanders check their vaccination status and get vaccinated for this infection,” he said.