Climate Change Brings Another "Surprise": More Diarrhea

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Climate Change Brings Another “Surprise”: More Diarrhea

Climate Change Brings Another “Surprise”: More Diarrhea

Current evidence suggests that many organisms will struggle to keep up with the pace of climate change on Earth.

Unfortunately for humans, some pathogens not only adapt to climate change but thrive in it, as indicated by a new study, including bacteria responsible for the common diarrheal disease, campylobacteriosis.

Climate Change Brings Another "Surprise": More Diarrhea

screenshot from PLOS Computational Biology

The culprit behind this debilitating zoonotic disease is the Campylobacter genus of bacteria. While there are 17 species and 6 subspecies of Campylobacter, the most common ones causing illness in humans are Campylobacter jejuni and Campylobacter coli, often transmitted to us through animal products.

British scientists explored how rising temperatures, prolonged sunlight, and increased humidity—side effects of current climate change on Earth—affect the spread of Campylobacter. The study reveals a significant correlation between the disease and global warming.

Giovanni Lo Iacono, Senior Lecturer in Biostatistics and Epidemiology at the University of Surrey, stated, “This information is invaluable because diseases like campylobacteriosis not only cause personal discomfort but also have significant societal impacts, leading to sick leaves and additional pressure on medical services worldwide.”

Researchers analyzed data from the UK Health Security Agency (UKHSA), including about a million cases of campylobacteriosis in England and Wales over two decades. Using a mathematical model that factored in weather data, they found a clear connection between the disease and climate.

Cases remained stable when the temperature was below 8°C (46°F), but for every 5°C (9°F) increase, cases steadily rose. Infection cases also spiked when humidity ranged between 75% and 80%. Longer sunlight exposure (over 10 hours) again showed higher infection rates, especially when combined with higher humidity. However, no correlation was found between the disease and variables such as rainfall or wind.

Lo Iacono explained, “We found a link between rising temperatures, increased humidity, and longer daylight hours with the transmission of campylobacteriosis. We are not entirely sure why this is the case. It could be that warmer weather enhances the survival and transmission of the pathogen, or it may be due to people’s behavior and social interactions during these periods.” He added, “However, what we do know is that climate change can have negative impacts on our health, not just on the environment.”

According to the World Health Organization, approximately one-tenth of the global population contracts campylobacteriosis each year, making it a major cause of diarrheal diseases. The risk of foodborne diseases like campylobacteriosis increases with the growth of more bacteria in the constantly changing environment.

Gordon Nichols, Visiting Professor at the University of Surrey, commented, “Environmental data can help us understand the complex patterns of disease transmission. Mastering this knowledge is crucial as it can help identify areas susceptible to potential outbreaks and ensure that resources are available to treat affected individuals, curbing the spread of the disease to other regions.”

The downside is that, although researchers have identified the link between climate change and the prevalence of campylobacteriosis, they are not entirely certain about the underlying mechanisms. This becomes their next area of research.

Lo Iacono said, “Since the time of Hippocrates, there has been a broad consensus that weather and climate can influence the spread of diseases. Understanding why and which specific environmental factors drive disease transmission is a complex question that hasn’t been fully answered. Now that we have a detailed description of how weather affects diseases, the next step is understanding the reasons. Importantly, with our transparent and conceptually simple approach, we can now assess the risk of infection diseases based on the recent local weather conditions.”

The research is published in the journal “PLOS Computational Biology.”