Microbes in motion: why understanding the role of disease-causing microbes is key to addressing environmental emergencies
ESR Chief Scientist Brett Cowan examines the emerging field of disaster microbiology, and how we’re incorporating this science into our broader work to prepare for and respond to natural disasters.
The flooding and Cyclone Gabrielle that struck Te Ika-a-Māui (North Island) this summer have wrought widespread devastation. Fifteen lives cut tragically short, thousands displaced, with billions of dollars in damage to New Zealand’s infrastructure and economy. These sorts of events are often labelled ‘natural disasters’, a phrase which conjures images of flattened homes and collapsed bridges. But it’s not always what we can see during a disaster that has the potential to harm us. These events also transform our environment at a microscopic level – with sometimes poorly understood consequences for our health.
That’s where the Institute of Environmental Science and Research (ESR) comes in. As the Crown Research Institute leading on science to improve the wellbeing of communities, we’re incorporating a ‘disaster microbiology’ approach in preparing for and responding to environmental crises. But what does this mean in practice?
Beyond the visible destruction of Cyclone Gabrielle, floodwaters carried pathogens from ground surfaces, septic tanks and sewerage systems into homes, businesses and fields. These pathogens can result in diarrhoeal, animal- and rodent- borne sickness, alongside skin and eye infections. In Aotearoa, an emerging concern is the bacterial disease leptospirosis (sometimes called ‘lepto’). Livestock and rats infected with this bacterium spread it through their urine, which can survive in mud and water for weeks. Cases of leptospirosis more than quadrupled in Hawke's Bay following Cyclone Gabrielle, with a spike in gastroenteritis and skin infections (due to cuts infected by contaminated water) across the North Island.
Meanwhile, water damage to homes and workplaces can promote the growth of toxin-producing moulds, resulting in respiratory illnesses known as ‘sick building syndrome’. At the same time, the potential for diseases linked with overcrowding grows as people are displaced from their homes.
We’re working to better understand the health risks of floodwater and leftover silt and debris. This includes for the agricultural sector – large swathes of which have been buried in mud in the aftermath of Cyclone Gabrielle. Our experts in public health, water and food contamination, alongside Iwi-led science delivery, are also exploring ways to build community resilience.
That’s a ‘sciencey’ way of saying, what do we know about the ways microbes spread through communities in Aotearoa following flooding? And based on what we’re learning, what steps can we take – from improved infrastructure to clearer health messages – to prevent harm and protect people’s wellbeing in the future?
This is an area where ESR has a track-record. Back In 2016, the town of Havelock North in the Hawke's Bay experienced a campylobacter outbreak spread through drinking water that affected more than 6,000 people. As a team, we used genomic sequencing to trace the infection to sheep faeces that had seeped into a local water bore following flooding. Investigating this case changed how we monitor and protect drinking water sources and led us to review the science informing national water standards. It also proved the value of developing innovative ways to prevent waterborne contamination.
While recent extreme weather in Aotearoa is front of mind, it’s not just flooding disasters that require attention at a microscopic level. Wildfires, dust storms, drought and extreme heat each promote adaptation in microbes in ways that have the potential to make us very sick. Because this field of science cuts across so many areas – public health, food and water safety and environmental protection – ESR is looking at how to better link health and environmental intelligence and surveillance with our country’s laboratory systems.
Climate change stress
Climate change is leading to rapid environmental shifts, which makes the field of disaster microbiology ever more important. On the one hand, microbes can be a harbinger of the ways in which our climate is changing. Take the marine bacteria Vibrio parahaemolyticus, which live in coastal environments. Shellfish absorb and accumulate these bacteria in their flesh. Waterborne pathogens like Vibrio love warmer temperatures, so as marine heatwaves increase, so does the population growth. Scientists, including at ESR, are studying Vibrio to better understand the impact of climate change on our environment.
At the same time, climate change is accelerating the adaptation of harmful pathogens in response to disaster-driven ‘stressors’. One big challenge is what's known as vector-borne diseases. With malaria, zika and Japanese encephalitis, the vector in question is the mosquito. As the climate warms and higher rainfall leads to more standing water for mosquitos to breed, this vector has the potential to change in unpredictable ways – for example the Japanese encephalitis virus was discovered in Australia’s south-east for the first time last year. Meeting the challenge of climate change – including its evolving health impacts – will require investigating macro level solutions, alongside a focus on the microscopic.
Weather events are inevitable, but the health impacts they have on society are not. One thing is clear in the wake of flooding and Cyclone Gabrielle this summer, we have a responsibility to step up with science-led solutions to protect our wellbeing. Not next decade or next year. Today.