From H5N1 in Australia to an Ebola outbreak in Africa, recent infectious disease events reinforce the need for constant vigilance. PHF Science Chief Scientist David Murdoch explores what these events can teach us about preparedness and why they matter for New Zealand.
One of the defining characteristics of infectious diseases is that they don’t always behave exactly as we expect. New pathogens emerge, familiar pathogens appear in unfamiliar places, and diseases we thought we understood reveal new challenges. The first half of this year has provided three timely reminders of that reality.
Highly pathogenic avian influenza (H5N1) was detected for the first time in wild birds in Australia. A hantavirus outbreak occurred aboard the Antarctic cruise ship Hondius. An outbreak of Ebola virus disease emerged in the Democratic Republic of the Congo (DRC), caused by an uncommon species of Ebola virus.
At first glance these events appear to have little in common. Yet each is an example of a zoonosis, an infectious disease that can be transmitted from animals to humans. Around 60% of known human infectious diseases are zoonotic, and most newly emerging infectious diseases originate in animals. While these diseases often capture public attention because of their novelty, they also remind us of something more important: infectious disease threats are remarkably diverse, and preparedness requires us to be ready for many different possibilities.
The recent detection of H5N1 avian influenza in Australian wild birds was significant, but not unexpected. The virus has spread extensively through bird populations across Asia, Europe, Africa, the Americas and even Antarctica over recent years; Australia was the last remaining continent free of this lineage. Although H5N1 has occasionally infected people following close contact with infected birds, it remains poorly adapted for sustained person-to-person transmission. For the general public, the current risk remains low. Nevertheless, its arrival in Australia has important implications for wildlife, agriculture and biosecurity, reinforcing the importance of continued surveillance across our region.
The hantavirus outbreak aboard the Hondius was unusual for a different reason. Hantaviruses are typically associated with exposure to infected rodents in rural environments and are certainly not viruses most people would associate with a cruise ship. However, the virus involved (Andes virus) is one of the few hantaviruses capable of spreading between people. Once an infected passenger boarded the vessel, the close-contact environment enabled transmission in a way that had rarely been observed before. The outbreak did not overturn established scientific understanding; rather, it demonstrated how known pathogens can occasionally behave in unexpected ways when circumstances align.
The Ebola outbreak in the DRC illustrates another type of challenge. Unlike previous major Ebola outbreaks caused by Zaire ebolavirus, this outbreak is due to Bundibugyo virus, a much less common species. Although it causes a similar severe illness, there are currently no licensed vaccines or specific antiviral treatments available. Public health authorities have therefore relied heavily on rapid laboratory diagnosis, surveillance, contact tracing, infection prevention measures and community engagement to limit transmission.
Importantly, none of these events currently represents a direct public health threat to New Zealand. However, they are highly relevant to us. New Zealand depends on international surveillance systems and rapid information sharing to detect emerging threats, understand their significance and determine whether they have implications for our population. As an island nation that relies heavily on international travel and trade, our health security is closely linked to what is happening beyond our borders.
These events also reinforce an important point about preparedness. It is neither possible nor practical to predict exactly which pathogen will emerge next. Instead, preparedness is about maintaining the capability to rapidly detect, investigate and respond to whatever threat presents itself. Sometimes that will be a virus expanding its geographic range, as with H5N1. Sometimes it will be a familiar pathogen appearing in an unexpected setting, as with the Hondius outbreak. At other times it will be a well-recognised disease caused by a less familiar virus, as with the current Ebola outbreak.
Maintaining that capability requires sustained investment in surveillance, laboratory science, epidemiology, clinical expertise and research. It also depends on New Zealand remaining closely connected to the international public health community. Organisations such as the World Health Organization, together with national public health agencies, specialist reference laboratories and international surveillance networks, provide the early warning systems, scientific expertise and coordination that enable countries to identify emerging threats and respond quickly. The rapid sharing of information, laboratory data and risk assessments between countries is one of the great strengths of the global public health system, and New Zealand both contributes to and benefits from these collective efforts.
Recognising this, New Zealand has recently established an Infectious Diseases Research Platform, hosted by PHF Science. By bringing together researchers and institutions from across the country, the Platform will strengthen national research capability, foster collaboration and generate the evidence needed to better detect, understand and respond to future infectious disease threats.
The three infectious disease events of 2026 are a useful reminder that the next significant threat is unlikely to look exactly like the last. That should not alarm us, but it should encourage us to remain vigilant. By staying connected to the international scientific community and continuing to invest in preparedness, New Zealand will be better placed to recognise and respond when the next unexpected event inevitably occurs.