There are multiple indirect consequences of globalisation and climate change, this article concerns one we all have first-hand experience with - zoonotic disease outbreaks.
Zoonotic diseases are diseases, caused by pathogens - these could be viral, bacterial, fungal or parasite - which jump from animals to human populations during a spillover event. COVID-19, Ebola, Marburg, and Rabies are all examples of zoonotic diseases. A seminal paper by Taylor et al. from 2001, found the majority (60%) of emerging diseases globally are zoonotic.
In 2016, a severe anthrax outbreak in Siberia saw the deaths of 2000 reindeers and one person. Anthrax is a zoonotic disease caused by the bacterial pathogen, Bacillus anthracis. Climate change induced permafrost thawing has meant anthrax has an increased likelihood of causing diseases in the arctic region; some researchers believe that pathogen carrying carcasses buried in the permafrost could thaw, reintroducing the diseases.
Additionally, deforestation causes the destruction of habitats of animals, some carrying disease, which then migrate into urban areas. Another seminal paper by Khalil et al. describes ‘the dilution effect’. This paper illustrates how decreased biodiversity leads to an increased risk of disease outbreaks.
An interdisciplinary framework, One Health, aims to understand the risks and propose potential solutions by unifying the health risk assessment of humans, animals, and the environment. To learn more about One Health, I interviewed Dr Charlotte Hammer an applied infectious diseases epidemiologist in the department of Veterinary Medicine and a fellow at Downing College.
‘The biggest project I am involved in right now is in West Africa, in Guinea, where we are looking at acute febrile illnesses [illness accompanied by fever] and trying to see how much of the burden is of a zoonotic nature – we are trying to find out what are the risks at the human-animal-environment interface and what is happening in these communities that is leading to diseases.’
‘We usually work with three types of different data. The first source is routinely collected surveillance data – diagnosis reported from doctors or labs – this is owned and developed by the country’s government. The second source is data from hospital settings – taking samples from patients coming into hospitals who have a fever and testing them for multiple pathogens of interest. The third part, where I am mostly involved, collecting data from the communities. We take blood samples to look for previous infections and secondly running questionnaires – asking people about their behaviours and interactions with animals. We are also taking samples from animals and interviewing animal owners about anything they may have noticed about their animals.’
‘I came from the human-side, working on mainly human diseases but if you are interested in zoonotic diseases still just within humans, you start to migrate to the One Health framework as it makes little sense to just look at the humans.’
‘To me, the great attraction of One Health is that we do not have just that one lens. It allows for multiple perspectives, it allows for multiple methodologies - all the way from very traditional epidemiology going so far as data science, machine learning, artificial intelligence. But on the other side also including very qualitative approaches such as ethnographic work, and everything in between. I think this gives it a richness that is academically very appealing.’
‘A lot of disease transmission is driven by how we as a society behave, what are values are what we place importance on. And that is something that as people coming from the sciences, we are often struggling to understand – we need sociologists, economists, and anthropologists to weigh in on this – there are very few disciplines that are not applicable to One Health.’
‘Infectious Diseases research at Cambridge is scattered around many departments – as wide as engineering, pathology, veterinary medicine, mathematics, zoology, plant sciences, medicine to name a few.’
In summary, globalisation and climate change have significantly contributed to zoonotic disease risk, globally. Additionally, the One Health framework symbolises a paradigm shift in the way we approach the human-animal-environment interface. It recognises that instead of attempting to overcome nature with a one-problem, one-solution mind set our survival necessitates that looking forward we must work with it, together drawing upon our understanding of multiple disciplines, with a multi-problem, multi-solution mind set.
If you are interested in learning more about One Health and the effect of climate change on zoonotic disease risks, there are many university societies such as One Health Society and Vegan Society hosting events related to these issues.
You can find out more about Dr Charlotte Hammer’s research on her college profile and on the department of Veterinary Medicine and Cambridge Infectious Diseases websites.
Papers referred to in this article include:
Taylor LH, Latham SM, Woolhouse ME. Risk factors for human disease emergence. Philos Trans R Soc Lond B Biol Sci. 2001 Jul 29;356(1411):983-9. doi: 10.1098/rstb.2001.0888. PMID: 11516376; PMCID: PMC1088493
Stella, E., Mari, L., Gabrieli, J. et al. Permafrost dynamics and the risk of anthrax transmission: a modelling study. Sci Rep 10, 16460 (2020). https://doi.org/10.1038/s41598-020-72440-6
Khalil, H., Ecke, F., Evander, M. et al. Declining ecosystem health and the dilution effect. Sci Rep 6, 31314 (2016). https://doi.org/10.1038/srep31314