New Study Reveals How Climate Change is Elevating Your Risk of Sewage-Borne Viruses

Climate change isn’t just about melting ice caps and rising sea levels. It can also increase your chances of coming into contact with viruses, especially those linked to sewage. Think about it: heavy rain and heatwaves are becoming more common, and these extreme weather events can mix raw sewage into our rivers, lakes, and coastal waters.

When storms hit, urban sewer systems often can’t keep up. This overload can lead to raw sewage being dumped directly into bodies of water. Research shows that viruses from this untreated sewage can linger for days, increasing health risks for anyone who comes into contact with these waters.

Raw sewage is a mix of human waste, food scraps, and harmful viruses. Some viruses, like enterovirus and norovirus, can be shed in huge amounts by infected people. Even after feeling better, individuals can still spread these viruses through their waste.

In the UK, wastewater treatment is generally effective. Most systems can eliminate over 99% of viruses. But even treated water can still carry some risk, releasing potentially harmful viruses into the environment every day. The dangers ramp up significantly when raw sewage is involved.

With climate projections indicating more extreme weather, including heavy rain and scorching heat, understanding how these changes impact sewage viruses is crucial. Recreational water enthusiasts are already facing risks from sewage and runoff pollution.

We’ve yet to fully grasp how weather affects a virus’s ability to infect humans and whether climate change could heighten these risks. Scientists need reliable methods to detect potentially infectious viruses. However, environmental samples can be messy, often containing chemicals and bacteria that complicate testing.

To tackle these issues, my team and I developed new techniques. We focused on purified viruses that could still cause infections, allowing us to study multiple virus types effectively. We experimented to see how climate change influences these sewage-associated viruses and the risks they pose to human health.

In our studies, we introduced viruses like adenovirus and norovirus into water samples from rivers and seas, observing how they broke down over two weeks. We simulated different temperatures and sunlight exposure to see how these factors affected the viruses’ survival.

We calculated “T90 decay rates,” which indicate how long it takes for virus levels to drop by 90%. Interestingly, the water type didn’t significantly affect how long viruses remained infectious. For example, some viruses could survive in seawater for up to three days at higher temperatures, and even longer in cooler water. Exposure to sunlight shortened their lifespan, with cloudy days allowing them to last about 2.5 days.

Our research suggests that to minimize infection risks, people should avoid swimming in contaminated waters for at least two and a half days after rain during cloudy weather, and at least 24 hours after sunny days. Climate change could make this situation worse, particularly in summer when sewage contamination might increase after heavy rains follow a dry spell.

This problem isn’t unique to the UK. Many countries still release untreated or inadequately treated sewage into their waters, creating a worldwide health issue. Our findings highlight the pressing need for improved sewage treatment practices everywhere, and for governments to create effective strategies to manage the growing threats posed by climate change.