Current evidence suggests many organisms will struggle to keep pace with a changing climate on Earth. However, unlucky for humans, some pathogens will not just adapt but thrive, including, as this new study suggests, the bugs that cause the common diarrhea illness campylobacteriosis.
The culprits behind the debilitating zoonosis disease are found in the Campylobacter genus of bacteria. While there are 17 species and six subspecies, the two that translate to human illness are most often C. jejuni and C. coli, generally spread to us from animal products.
UK scientists investigated how elevated temperatures, longer days and increased humidity – all side-effects of Earth’s current climate change – impacted the transmission of Campylobacter bacteria, and found a significant association with illness and a warming planet.
"This information is invaluable, as illnesses such as campylobacteriosis not only cause discomfort to individuals, but have enormous societal impacts, with people having to call in sick to work and puts extra pressure on health services across the world,” said Giovanni Lo Iacono, senior lecturer in biostatistics and epidemiology at the University of Surrey.
Researchers analyzed UK Health Security Agency (UKHSA) data that featured around a million campylobacteriosis cases in England and Wales across a 20-year period. Using a mathematical model that factored in comparative weather data, the team found a clear link between illness and climate.
While cases remained stable when temperatures were below 8 °C (46 °F), cases increased steadily for every 5 °C (9 °F) rise in temperature. There was also a spike in infections when humidity was between 75% and 80%. Finally, longer days (more than 10 hours of solar light) again revealed a higher rate of infection, even more so when it was also linked with higher humidity. However, they found no link with illness and rain or wind variables.
"What we have found is that rising temperatures, humidity and increased day length are associated with the spread of campylobacteriosis,” said Lo Iacono. “We do not fully understand why this may be. It could be that warm weather increases the survival and spread of pathogenic bacteria (so the weather causes the disease) or alternatively it could be people's behavior and how they socialize during such periods.
“However, what we do know is climate change not only has an environmental impact but has the potential to negatively affect our health by aiding the spread of infectious diseases,” he added.
Around one in 10 people around the globe currently fall ill with campylobacteriosis each year and it is one of the key causes of diarrheal disease, according to the World Health Organization. Most frequently transmitted through undercooked poultry, other meat and meat products, as well as contaminated (and raw) milk, water and ice, infection is extremely unpleasant. Symptoms of diarrhea, abdominal pain, headache, nausea, vomiting and fever usually last three-to-six days, but can stick around for 10 days. More bacteria able to thrive in a changing environment raises the risk of food-borne illnesses such as campylobacteriosis.
"Environmental data can help us understand complex patterns in the spread of diseases,” said Gordon Nichols, visiting professor at the University of Surrey. “Having this knowledge is invaluable as it can help us identify areas vulnerable to potential outbreaks and ensure they have the resources available to treat people affected and to curb the spread of disease into other areas."
The bad news, however, is while researchers have established a link between climate change and campylobacteriosis prevalence, they’re not entirely sure of the mechanism behind it. Which is their next path of study.
"Since Hippocrates, there has been a large consensus that weather and climate influence the spread of diseases,” said Lo Iacono. “Getting to the bottom of why this is and what specific environmental factors drive the spread of disease is a complicated matter and not fully understood.
"We now have a detailed description of how the weather affects the disease, and the next step is to understand the why,” he added. “Importantly, through our transparent and conceptually simple approach, we can now tell the risk of getting the disease when we know the recent local weather.”
The study was published in the journal PLOS Computational Biology.
Source: University of Surrey via MedicalXpress
