Bird flu breakdown: Is there cause for concern in NZ?

Bird flu has been around for decades but recent developments in its spread have made the world sit up and pay attention. So, what do we need to know about avian influenza and what could it mean for New Zealand if it does reach our shores?

The highly pathogenic H5N1 virus, otherwise known as bird flu, has made global headlines for a few reasons in 2024.

First, it was detected in mainland Antarctica in February, leaving New Zealand, Australia and the Pacific Islands as one of the only regions globally yet to record any cases of the virus in its wildlife.

Then, just weeks later, bird flu spread to cows for the first time, with dozens of herds in the US recording the virus.

And that really made the world’s scientists sit up and take notice.

Bird flu is causing concern because it’s evolving and changing its genetic code, says University of Otago virologist Professor Jemma Geoghegan.

“Before, [the virus] was quite confined to its host range and now the genetic mutations have allowed it to broaden that host range to a whole bunch of different bird species, but it's also spilled over to mammalian hosts as well,” she told 1News.

Geoghegan says experts initially thought these spillovers into mammals such as marine animals, cats, dogs and goats were dead-end spillovers, but early evidence from the ongoing cattle outbreak in the US suggests there may have been widespread transmission between those cows.

“Every time [the virus] transmits in mammals, it is under quite strong selection pressure to then be better at transmitting between mammals,” she said.

“We've seen this before ... especially in livestock like pigs; pigs were responsible for the emergence of swine flu back in 2009.

“These mammals act as a sort of mixing vessel so that influenza viruses can swap genetic material ... and become better at spreading between mammals.”

There have been nearly 900 human cases of the H5N1 virus globally since 2003, according to the World Health Organization.

So far, those cases have arisen through contact with infected animals rather than transmission between humans.

However, the mortality rate in those cases is of more concern. Just over half (52%) of the people known to have caught the virus have died.

There’s not very good evidence to suggest bird flu spreads between humans yet, Geoghegan said.

“[But] if there is ongoing transmission between mammals, it just increases the likelihood that the virus will adapt to human-to-human transmission, so that could also now be a problem for a human health pandemic as well.”

Geoghegan said it’s a concerning situation, with scientists and public health experts around the world keeping a very close watch on proceedings.

She added that it was bad timing having these latest bird flu developments come so soon after Covid-19.

“People are sort of exhausted from dealing with infectious disease.”

New Zealand authorities are already monitoring for H5N1 on our shores and planning for that scenario.

If the highly pathogenic bird flu was detected here, Biosecurity New Zealand would be the lead agency coordinating the response, alongside the Department of Conservation and the Ministry of Health Te Whatu Ora.

While the country has certain border controls in place, preventing bird flu from arriving in New Zealand presents unique challenges, says Mary van Andel, Chief Veterinary Officer at the Ministry for Primary Industries.

“[The virus] has been spreading [around the world] with wild birds and, of course, we can't control if those wild birds come to New Zealand or not,” she said.

“So, we need to make sure that we keep gathering information, knowing where the disease is and where it isn't.

“Early detection ... will allow us to effectively work together with those other agencies to minimise impacts on industry, on biodiversity, and make sure that there aren't spillover events to humans wherever we can.”

Given the virus has killed hundreds of millions of birds around the world since it was first discovered, New Zealand’s poultry industry is already working on biosecurity measures should H5N1 arrive here.

And with the news that bird flu has spread to cattle in the US, van Andel said DairyNZ is also focused on preparing for the virus.

“[It is] making sure farmers know what good biosecurity on farms looks like, because that will decrease the likelihood of a spillover event happening, but also make sure that if that did happen, it didn't spread any further,” she said.

Authorities in the US have not had to resort to culling cattle, van Andel said.

“Our colleagues in the US are telling us that [infected] cattle are recovering in about 10-14 days.”

Van Andel said New Zealand farmers know their cows and would get in touch with their veterinarians if they noticed anything unusual within their herd.

“We've got good communications in place with private veterinary practitioners about what to look out for [when it comes to bird flu],” van Andel said.

“Those vets are out there on the frontline and ringing our exotic pest and disease hotline on a regular basis when they see other things that worry them and this is just another thing that's different that they would ring in.”

Both van Andel and Geoghegan are encouraging New Zealanders to let authorities know if they see a group of birds that are sick or dead.

People can report these by calling the exotic pest or disease reporting hotline on 0800 80 99 66. Members of the public shouldn’t go near the affected animals themselves.

Geoghegan said the biggest danger bird flu currently presents to New Zealand is to its wildlife.

She said this is why the Department of Conservation is currently trialling a vaccine for some of the country’s threatened native species, including birds such as the takahē and kākāpō, in certain captive facilities.

“New Zealand has a lot of native birds that are only found in New Zealand, and they're really treasured taonga species that need to be protected,” Geoghegan said.

“That’s kind of the biggest threat to New Zealand at the moment. [Bird flu] is a public health [concern] but it’s way more of a problem for wildlife at the moment.”