Climate change and arthropod vectors – new research shows that climate change is causing the diffusion of the arthropod vectors in higher elevations and latitudes
Climate change’s implications on human health are visible, as food insecurity, displacement, and physical injuries come with the rising temperatures and the increased frequency and intensity of extreme weather events, such as floods and droughts.
The impact of climate change on the climate can be felt before birth, as highlighted by a 2022 study by researchers from the Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene & Tropical Medicine (LSHTM) and the LSHTM published in The Lancet Planetary Health.
Increasing in diseases – estimations from the World Health Organization (WHO)
The researchers found that the fetal strain increased by seventeen percent for every one degree Celsius of increment in heat stress exposure in a group of ninety-two pregnant subsistence farmers in The Gambia.
In addition to its direct health impacts, climate change has influenced and harmed human health through its plurality of effects on the threat of diseases. It has been estimated by the World Health Organization (WHO) that by the time between 2030 and 2050, climate change will cause about 250 000 additional fatalities each year due to malnutrition, malaria, diarrhea, and heat stress.
These health risks have a disproportionate incidence across populations, as the vulnerability factors influencing one’s chances to be affected by climate change impacts on their health are demographic, geographic, socioeconomic, and biological, along with their health status and socio-political conditions, reflecting and exacerbating inequality.
The influence of climate change-related hazards on the status of human pathogenic diseases
Climate change, along with factors like urbanization, globalization, and changes in land use, is speeding up the spread of water-borne, food-borne, and vector-borne diseases and zoonoses, leading to an augmented threat of malady and demise.
The impact of climate change on pathogenic disease is cause for concern as human vulnerability to pathogenic diseases is substantial, as shown by the economic and social disruption brought over by the emergence of the COVID-19 pandemic.
A 2022 study conducted by researchers from the University of Hawaiʻi at Mānoa and the University of Wisconsin-Madison looked at the effects of ten climate-sensitive hazards caused by Greenhouse Gas (GHG) emissions on known pathogenic diseases affecting humans, such as Aseptic meningitis, Adenovirus infection, Avian influenza, and Typhoid fever.
infectious diseases have been aggravated by climatic hazards
They found that climate-related hazards, including temperature increases and precipitation changes, have caused a significant aggravation of these infectious diseases affecting humanity.
In fact, the group of pathogenic diseases aggravated by climatic hazards represented fifty-eight percent, with 218 of the 375 infectious diseases documented to have impacted humanity found to have been aggravated by climatic hazards.
«We carried out three complimentary literature searches following Prisma guidelines for reviews. For our search, we specifically look for empirical case examples where a specific climatic hazard influenced a specific disease in a specific place in time. We use Google Scholar to find our papers. In the first search, we did search the word ‘disease’ with each of the ten climatic hazards. In the second search, we looked for each of the ten climatic hazards and diseases in the Gideon and CDC databases. This meant that we looked at a total of 300 and 75 diseases in all, and then for the final search, we wanted to confirm we didn’t miss any diseases, so we also then searched diseased and pathogen name synonyms».
Dr. Tristan McKenzie, one of the study’s authors, explained at an event organized by the Pacific Regional Invasive Species and Climate Change (Pacific RISCC) Management Network.
Improving suitability for pathogens’ reproduction
«We see that warming was associated with aggravating the greatest number of diseases, that is, 160 diseases. Vector-borne transmission was the most common transmission pathway responsible for aggravating 103 diseases, and viral diseases were the most aggravated, in total, seventy-six diseases. Breaking this down a bit further, we found that fifty-eight percent, that is, 218 out of 375 diseases impacting humans are aggravated by climate change. Of the documented cases of diseases influenced by climate change, seventy-eight percent were exclusively aggravated by climate change, with only three percent exclusively diminished. In addition, we found over 1000 pathways for climatic hazard-driven disease transmission».
Increased risk of infection, and decreased human ability to deal with pathogens
For this study, it emerged that climate-related hazards are playing a role in bringing people and pathogens closer, increasing the risk of infection, and have decreased human ability to deal with pathogens by changing body condition, causing exposure-related stress, through imposing hazardous circumstances on individuals, compromising physical infrastructure, and hindering people’s access to health care.
The same climate-change-related hazards result in improved suitability for pathogens’ reproduction, faster life cycles, and extended exposure season, escalating the interactions between vector organisms and pathogens and boosting virulence.
Climate change and arthropod vectors
In addition to these phenomena, climate change is causing the diffusion of the arthropod vectors in higher elevations and latitudes.
Georgetown University scientists’ 2023 study Rapid range shifts in African Anopheles mosquitoes over the last century looked at this phenomenon through a dataset comprising almost twelve decades.
Their findings showed that Anopheles mosquitoes had undergone sizable range shifts over the last century, with their southern range maxima shifting away from the Equator at an estimated pace of 4.7 kilometers per year, while their altitudinal gain per year amounted to an estimated rate of 6.5 meters.
In Europe, in 2022, France registered 65 autochthonous cases of dengue, surpassing the number of cases recorded between 2010 and 2021.
The relationship between antimicrobial resistance (AMR), climate change, and pollution
Antimicrobial resistance (AMR) is the ability mastered by strains of pathogenic microorganisms such as bacteria, viruses, fungi, and parasites to withstand the effects of antimicrobial treatments such as antibiotics used to treat diseases affecting human beings, animals, and plants.
The existence of AMR has become one of the principal public health challenges of the current century (Prestinaci, 2015), as it impacts health systems’ ability to treat a range of infections.
Pathogenic microorganisms can develop resistance to the antimicrobial medications used to eliminate them when they come in contact with them.
The link between antimicrobial resistance and environmental pollution
This global health concern stems from the overuse and misuse of antibiotics and other antimicrobial drugs and inadequate infection control and prevention. According to the United Nations Environment Programme (UNEP), antimicrobial resistance could cause ten million deaths each year by 2050. This is the number of deaths caused by cancer, a leading global cause of death, in 2020.
Antimicrobial resistance has been linked to environmental pollution, climate change, and other human activities. The higher temperatures caused by global warming have been connected with a rise in antimicrobial-resistant infections (Pepi, Focardi, 2021).
Environmental contaminants, storms, and precipitations
A 2023 study by researchers from the Department of Medical and Surgical Sciences and Advanced Technologies GF Ingrassia of the University of Catania published in the International Journal of Public Health and Environmental Research analyzed the link between Antimicrobial Resistance and climate change. This study highlighted the intertwinedness of these two global health emergencies, with factors such as environmental contaminants, storms, and precipitations involved in the relationship between them.
Their research showed that the COVID-19 pandemic has further complicated the picture by influencing the use of antibiotics, personal protective equipment, and biocides. This has, in turn, led to increased contaminant concentrations in bodies of water.
One Health response to antimicrobial resistance
The report “Bracing for Superbugs: Strengthening environmental action in the One Health response to antimicrobial resistance” by the UNEP highlighted how the understanding and response to AMR cannot happen in isolation from that of climate change, waste and pollution and biodiversity loss as all these phenomena are born from consumption and production patterns incompatible with planetary health.
«The environmental crisis of our time is also one of human rights and geopolitics – the antimicrobial resistance report published by UNEP today is yet another example of inequity, in that the AMR crisis is disproportionately affecting countries in the Global South countries», said Mia Amor Mottley, Barbados’s Prime Minister and Chair of the One Health Global Leaders Group on Antimicrobial Resistance in a statement.
Raising awareness by placing the AMR crisis on the agenda of the world’s nations
«We must remain focused on turning the tide in this crisis by raising awareness and by placing this matter of global importance on the agenda of the world’s nations».
«Pollution of air, soil, and waterways undermines the human right to a clean and healthy environment. The same drivers that cause environment degradation are worsening the antimicrobial resistance problem. The impacts of antimicrobial resistance could destroy our health and food systems», said Inger Andersen, UNEP’s Executive Director, in a statement. «Cutting down pollution is a prerequisite for another century of progress towards zero hunger and good health».
The United Nations Environment Programme (UNEP)
Organization that coordinates responses to environmental issues within the United Nations system.
