A classic kiwi summer. A quick dip at the beach. A bucket full of shellfish. A plan for an easy whānau dinner. Yet, we must be careful of the tiny pathogens we cannot see.
In coastal and freshwater environments across Aotearoa, Vibrio bacteria live naturally in our waters. Vibrio are a part of the ecosystem and often live alongside other organisms without causing harm. The challenge is that some Vibrio can also make people sick.
Vibrio infections can look different from person to person. Some people get an intestinal illness, often after eating raw or undercooked seafood. Others develop wound infections if seawater gets into a cut. Ear infections can happen too, especially after time in the water. In severe cases, illness can lead to hospital care and in rare situations, death.
The full picture of vibrio-related illness in Aotearoa has been hard to understand. That is because only some Vibrio infections illnesses are nationally reported under current rules, including cholera and acute gastroenteritis caused by Vibrio parahaemolyticus. This means we have had less visibility of other Vibrio species and the illnesses they may be causing.
It is this gap in vibrio knowledge that PHF scientists set out to explore in the study Vibrio infections in Aotearoa (1998–2024) and the effect of current disease reporting structures. Our scientists brought together national surveillance data, hospital discharge information and diagnostic laboratory results from across Aotearoa. What they found backs their hypothesis. Vibrio illness here involves a wider range of species than routine reporting has captured, including some infections that are very serious.
One species stood out for its severity, Vibrio vulnificus. Also seen in other parts of the world, Vibrio vulnificus infections can lead to serious illness, where people need surgery and other life-saving interventions. Across all New Zealand hospital discharge records, 40 per cent of patients with vibrio infections also had other health conditions such as diabetes or hepatitis. Results like this remind us that risk is not shared evenly and that prevention matters most for people who are more vulnerable.
If you have ever tried to settle a child with a sore ear after a day at the beach, you will know how quickly a fun day can change. PHF Science’s study also discovered that Vibrio alginolyticus was often found in ear swabs, particularly from children. In many cases other bacteria were present too, which suggests vibrio may not always be the only cause.
The study raised another new challenge for Aotearoa. People were becoming ill from Vibrio cholerae. This species is famous for cholera, but the toxin-forming strains that cause cholera are not circulating in Aotearoa. The concern here is non-toxin forming strains that can still cause illness and can be found in freshwater and coastal environments. So how are people in Aotearoa being exposed? That question is part of the next phase of work.
What we do know is that vibrio thrive in warmer conditions. As water temperatures rise, conditions can become more favourable for these bacteria. The threat of climate change is prompting scientists to investigate better monitoring and prevention methods.
Further research into connections between environmental conditions and Vibrio illnesses is being led by scientists within the Food and Risk Assessment team in Christchurch. This study, funded by the Ministry of Business, Innovation and Employment (MBIE) on behalf of the Government, aligns with vibrio research from other organisations, working towards one goal: to develop an early warning approach that can help predict periods of higher risk and support better public health decisions.
World Food Safety Day is about confidence as much as caution. We want people to enjoy kaimoana, beaches and summer BBQs with whānau, while also feeling safe and protected by the science working alongside this changing world.
Don’t let Vibrio ruin your summer. New Zealand Food Safety have provided some simple tips here.