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Chapter 2. Natural ecosystems altered and damaged by climate change: a threat to human health

Spillover: From climate change to pandemics

Mary E. Wilson
p. 58-64

Abstract

Climate change will increase human infections and the risk of pandemics by affecting pathogenic microbes, their environmental reservoirs and animal hosts, and the mosquitoes and other vectors that transmit them. Climate-induced movement of arthropod vectors and range shifts of wildlife will place larger populations at higher risk for infectious spillover events. Recent epidemics and pandemics (e.g., HIV/AIDS, Covid, SARS, mpox, Ebola) have all originated from wildlife viruses carried by bats, rodents and other animals. While some areas in Africa are projected to become too hot for malaria transmission, changing climate will allow expansion of Aedes-transmitted viral infections, such as dengue, chikungunya, and Zika, into areas with large urban populations. Animals and plants are themselves susceptible to die-offs and even extinction from infections, jeopardizing food security and health.

Another unknown is whether the vast permafrost, now melting, could become a source of novel microbes that are pathogenic for humans.

Travel, trade, and migration contribute to the global movement of human and animal pathogens and vectors. These forces will be amplified by climate change, and climate-related loss of biodiversity will make ecosystems less resilient to invasive species.

A One Health approach - considering together humans, animals, plants, and the shared environment – can inform surveillance, monitoring, research, and response, and help preserve human well-being while protecting the planet.

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Full text

Introduction

1Infections are multiplying. Pathogens causing many of these infections are viruses typically found in wildlife. Since 2020, massive die-offs of birds related to H5N1 influenza virus have been observed, and more than 50 species of mammals have been infected. Several well-known mosquito-borne viral infections, such as dengue, chikungunya, and West Nile infections, are similarly expanding.

2The Covid pandemic has killed millions, disrupted daily life, and exposed vulnerabilities in global systems for public health, health care, food security, governance, political discourse, and equitable sharing of resources.

3This article explores how climate change can be expected to affect the appearance and progression of outbreaks and epidemics, even the resurgence of old diseases. Discussion will focus on spillover events—transfer and establishment of infection from one species to another—and vector-borne infections, and give the tools to aid understanding and mitigation of microbial threats to health. A One Health approach, that embraces humans, animals, plants, climate, and ecosystems, offers insights to build the necessary global, integrated surveillance and response systems.

Spillover events

4A network of biological interactions underpins the development of infections in humans and animals; these biological systems are responsive to temperature, rainfall, humidity, and environmental conditions. Many infections, such as salmonella or campylobacter routinely spread from animals to humans. These are known as zoonoses, and most have been occurring for centuries.

  • 1 Plowright, R.K., et al. (2017) Pathways to zoonotic spillover. Nature Rev Microbiol 15(August):502- (...)

5Many recent pandemics have been caused by animal viruses that have more recently spilled over into humans (e.g. SARS, MERS, Covid, HIV/AIDS). A spillover event refers to the transfer of a microbe from one species to another and establishment of infection.1 After such an event, some pathogens use a vector, like a mosquito, to spread to other humans and/or animals. Most spillover events leading to epidemics have been caused by viruses, but they can involve bacteria and other types of pathogens.

6Occasionally spillover events with novel microbes for which humans have no immunity can spark epidemics and pandemics. It is thus important to understand the drivers of spillover, including such factors as climate change and human behavior, and to identify ways to mitigate them.

7Viruses and other microbes that live harmlessly in one animal species may cause deadly diseases in others. Bats carry a number of viruses that can cause severe disease in humans. They can be transmitted directly by bite, or after they have infected another animal, as occurred with SARS-CoV-1 (cause of SARS pandemic in 2003), which infected palm civets, and MERS-CoV, which infected camels and then spread to humans. The Nipah virus, which can cause fatal encephalitis in humans, can infect pigs, in which the virus amplifies and can then spread to farmers or can contaminate date palm sap when bats feed on the sap being collected for human consumption. The virus also occasionally spreads from person-to-person under conditions of extremely close contact.

Bats

Bats, the only mammal that flies, are the source of several viruses that have caused severe epidemics in humans. Scientists are eager to understand how they can carry these viruses without showing obvious signs of tissue damage. Bats are old evolutionarily, widely distributed (all continents except Antarctica), abundant (>1400 species and constitute about 20% of all mammals), varied, ranging from the 2-gram bumblebee bat to flying foxes with wing spans of 6 feet. They live in colonies that may have tens of thousands or even millions of bats. They migrate to seek food. Some hibernate during harsh conditions, often in caves. They are active at night and navigate using echolocation. They live longer than other mammals of similar size, often 7-8 years or even longer.

Many consider bats as shadowy, dark figures but they serve critically important roles, pollinating plants, spreading seeds, and consuming insect pests that destroy crops. Their diet includes insects, small mammals, fruit and nectar. Consumption of partially eaten fruit contaminated with bat urine and feces by pigs in Malaysia may have been the route that infected pigs with Nipah virus, who passed infection to pig farmers. In many areas of the world clearing of land for agriculture or development has displaced bats from habitats where they live or feed. This has increased the contact of bats with human and domestic animal populations.

8Household pets often share microbes with their human companions. Microbes from food animals, like salmonella and campylobacter, regularly reach humans via meat, milk or eggs, following long-established pathways that typically do not introduce novel pathogens into the human population. The growing global demand for animal protein has led to industrial farming where animals, especially swine and chickens, are raised by the thousands in concentrated areas. Globally the biomass of food animals now exceeds that of all humans. In many regions, wild animals are intensively farmed for fur, food, and other products. Wild animals introduce multiple possible pathways of spread of novel pathogens to humans: animal bite (e.g., rabies), inhalation of microbes in the air (possibly influenza, coronaviruses), eating or drinking contaminated animal products, etc. Live animal markets selling wild animals, such as the palm civets infected with the bat-origin-SARS coronavirus in 2003, may provide the intermediate hosts through which pathogens in other wildlife reach humans. Bats are also hunted and eaten in some cultures. Novel connections pose new risks.

9Some economic development practices have expanded opportunities for spillover events at the human-wildlife interface by bringing species into contact that would not normally interact. These practices include land use change (often for agricultural expansion to support livestock production), encroachment on habitats and displacement of species (such as bats), wildlife farming and trade, live animal markets where multiple different species of wild animals may share crowded stalls, and global travel and trade.

10Spillover of a virus into a mammalian host provides opportunities for viral evolution and potential spread. While most spillover events do not lead to epidemics or pandemics, notable ones, like HIV-1 spilling over from chimpanzees in Central Africa in the 1900s, have had devastating global consequences. The virus did not disperse globally until later in the century when many factors, including travel, trade, injection drug use, broad dissemination of blood products, and change in sexual mores, fueled a pandemic that killed millions.

Species range shifts

  • 2 Carlson, C. J., Albery, G. F., Merow, C., et al. (2022). Climate change increases cross-species vir (...)

11Many species live in specific geographic areas, defined by ecoclimatic conditions that allow optimal survival. Climate change is shifting the geographic range and distributions of species, including insects, and changing pathways for migratory animals, all creating more opportunities for novel interactions across species.2

12Crossing the species barrier can be difficult. Many cultural, behavioral, biological, environmental, and immunological barriers inhibit the successful passage and establishment of a microbe from one species to another - and then its global spread. Physical proximity and contact are necessary but not sufficient. The common methods of entry into a human are through the air, from food/drink, or through the skin or mucous membranes. Entry via the skin may be accomplished by an arthropod vector, such as mosquito or tick, or by breaking of skin by trauma. Many microbes carried by animals cannot establish infection in a human host. Viruses must be able to attach to and enter a cell and take over cellular processes to survive and replicate, but human tissues may not have cells with receptors that allow attachment of the virus. Whether infection will follow direct contact with a microbe depends on microbial and host factors (such as abundance of microbe, site of contact, virulence of the microbe, susceptibility of the host, and immune response). The outcome of infection also depends on both host and microbe factors.

13Only rare pathogens have the capacity to cause severe disease in humans and to spread globally sparking an epidemic or pandemic. For infection to be propagated to other humans or animals, the infecting microbe must have a way to exit the body, to survive, and to reach susceptible hosts. Among the most successful in leading to pandemics are those organisms that spread by the respiratory route (SARS, influenza, Covid) and those that are sexually transmitted (HIV, mpox – formerly called monkeypox). If a virus can be transmitted before it causes symptoms (or if it never causes symptoms), it can spread much more successfully.

Vectorborne Diseases

West Nile virus

In the United States in 1999, an unusual number of dead crows were observed in New York during the same month when an unusual number of cases of encephalitis and deaths were being seen in hospitalized patients in the same area. After a few weeks, a flavivirus, West Nile virus, never previously known to be present in the US was identified. It was spread by locally abundant mosquitoes from bird to bird; mosquitoes could also infect humans. Already present in the US were mosquitoes competent to transmit the virus and susceptible birds and humans.
The virus spread westward across the US, reaching California by 2002. By 2004 every state in the contiguous US had reported West Nile virus infections in humans or animals.

  • 3 Mora, C., McKenzie, T., Gaw, I.M., et al. (2022) Over half of known pathogenic diseases can be aggr (...)
  • 4 de Souza, W.M. &, Weaver, S.C. (2024) Effects of climate change and human activities on vector-born (...)

14While climate change will have diverse impacts through direct and indirect mechanisms on multiple infectious diseases in humans, the impact on vectorborne diseases (VBD) is expected to be widespread and serious.3 4 VBD are infections spread to humans by bites of bloodsucking (hematophagous) arthropods, including mosquitoes, ticks, sandflies, midges, blackflies, and triatomine bugs. These arthropods can transmit infections caused by viruses, bacteria and parasites, like malaria. More than 6 billion humans live in areas at risk for vectorborne infections. Globally an estimated 700,000 people die annually from vectorborne infections, with malaria accounting for the largest number. Other prominent and deadly VBD include yellow fever, dengue fever, African sleeping sickness, West Nile fever, and Japanese encephalitis. Animals are also affected by VBD.

15Arthropod vectors, like mosquitoes, can carry a pathogen from an animal to a human (e.g., West Nile virus) or from one human to another (e.g., malaria). Mosquitoes are not simply flying syringes or passive transporters of infected blood. Vector transmission requires a complex biological interaction involving the pathogen and at least two hosts, the arthropod and the human. For an infection to be transmitted by a vector, the pathogen must be able to infect and to multiply in both the arthropod and in humans, and sometimes also in an intermediate or reservoir host, like a bird or nonhuman primate.

16For example, after a mosquito takes a blood meal from a bird infected with West Nile virus, the virus must infect the mosquito tissues, replicate (multiply), and then disseminate to its salivary glands so that when the mosquito takes another blood meal, virus can be passed to a new host.

17The process takes time (days to more than a week, depending on the pathogen and the temperature), and compatibility between pathogen and arthropod is necessary. More than 3500 species of mosquitoes have been identified. Most do not feed on humans and many that can bite cannot transmit infection. Only a limited number of species are competent to transmit a given virus, parasite, or other pathogen. Plus, a mosquito may not live long enough to take another blood meal or may not find another human to bite.

18VBD are climate-sensitive infections. Arthropods are ectothermic, meaning they assume the temperature of the ambient environment. Every part of the life cycle of the mosquito (or other arthropod) is affected by the environment. Temperature, rainfall, and humidity affect rates of development, survival, biting rate, abundance, and, critically important, the extrinsic incubation period. The latter is the time it takes for the pathogen (virus, parasite) to infect and replicate within the mosquito and reach the salivary glands, so that it can be transmitted to another host. Up to a point, warmer temperatures lead to shorter extrinsic incubation periods, meaning more mosquitoes survive long enough to transmit infection. However, in a cooler environment, a mosquito may die before the pathogen replicates and disseminates. Extreme weather events also affect mosquito survival, distribution, and abundance. Flooding can provide water that is essential for breeding, but it can also destroy breeding sites. Winds can carry mosquitoes to new areas. Some mosquitoes have evolved mechanisms to survive prolonged dry periods.

  • 5 Mordecai, E.A. et al. (2019) Thermal biology of mosquito-borne disease. Ecol Lett 22:1690-1708. Doi (...)
  • 6 Kuperschmidt, K. (2023) Feeling the heat. Science 2023;381(issue 6665):1388-92, p.1390.

19Thermal performance curves can be used to describe the thermal tolerance range and the optimal performance range for arthropods.5 Each mosquito species has optimal ranges for survival, reproduction, and biting activity. Each vector-pathogen pair has its optimal thermal ranges (Figure 1).6

Figure 1: Optimal temperature ranges for mosquito-borne diseases by disease-vector combination

Figure 1: Optimal temperature ranges for mosquito-borne diseases by disease-vector combination

Source: Kuperschmidt, K., 2023

20Ticks have a longer development cycle and live longer than mosquitoes but are also affected by temperature, rainfall, and humidity. Upper and lower lethal temperatures and thermal preferences vary by tick species.

  • 7 de Souza, W.M. &, Weaver, S.C. (2024) Effects of climate change and human activities on vector-born (...)

21Climate change is expected to shift the geographic distribution of many important vectors of human infections and alter the intensity of transmission. The general trend for changes in distribution will be a shift of transmission to higher latitudes and to areas of higher elevation. The projected, expanded distribution will include many densely populated areas (Figure 2).7

Figure 2: Potential impacts of climate change on the geographical distribution of vectors

Figure 2: Potential impacts of climate change on the geographical distribution of vectors

Source: de Souza et al., 2024

22Transmission of many vectorborne infections is seasonal in temperate areas, occurring during the warmer summer months, while in tropical areas it may peak during the rainy season. With climate change, periods favorable for transmission will lengthen and, in some areas, may allow year-round transmission. Arthropod populations that usually decline in cold winter conditions, may survive during milder winters. Climate change will also influence reservoir and intermediate hosts such as rodents, birds, and bats involved in VBD.

23Each mosquito species has specific habitats and behaviors, such as feeding time, that influence its capacity to transmit infections. Aedes aegypti, which now infests tropical and subtropical areas, is exceptionally well suited to transmit infections to humans. It thrives in urban environments, breeding in flower pots, discarded plastic cups, used tires, and other sites found widely in cities. It prefers human blood and will feed on more than one person if its feeding is interrupted. It bites during the daytime, so bednets offer no protection. In areas where piped water service is unreliable and residents store water in their homes, these water receptacles provide an ideal, in-house breeding site for mosquitoes. Control has been difficult, and this mosquito is a competent vector for multiple major human pathogens, including dengue, yellow fever, Zika virus, and chikungunya virus.

24Humans facilitated the spread of mosquito vectors globally through travel and trade and have provided habitats that support their continued survival. The confluence of urbanization, massive uncontrolled growth of cities in tropical and subtropical areas, travel and migration that allow the movement of the virus in human hosts and reintroductions, have contributed to worsening epidemics of dengue infections in tropical and subtropical areas globally.

  • 8 Mordecai, E.A., et al. Ryan, S.J., Caldwell, J.M. Shah, M.M., LeBeaud, A.D. (2020) Climate change c (...)

25Up to a point, warmer temperatures can favor increased transmission of vectorborne infections. Performance of a key malaria-transmitting mosquito, Anopheles gambiae, peaks at 25°C, whereas transmission of dengue virus by Aedes aegypti peaks at 29°C. With global warming, parts of west and central Africa are projected to become too warm for efficient malaria transmission. This may make malaria control and eradication easier to achieve. Other infections, such as dengue, may replace malaria as major threats to local populations.8

26Other factors can limit or worsen the burden of transmission of vectorborne infections. These include type of housing, presence of screened windows and air conditioning, source of water in households, availability of treated bednets in areas with malaria transmission, and local mosquito control activities. The mosquitoes that commonly transmit malaria in Africa bite at night, and sleeping under a bednet can provide considerable protection.

Dengue

Reported dengue cases have increased more than ten-fold in the past two decades. The world is currently experiencing widespread epidemics, the largest ever reported, with more than 10 million cases in WHO regions as of July 2024. One can expect to see more introductions (human carriers) into nonendemic areas that are infested with competent mosquitoes, like France and parts of southern US, that will spark local outbreaks. Housing with screens and air conditioning can reduce risk of infection for local residents.
Four different serotypes of dengue virus infect humans. An unusual feature of dengue is that infection with one serotype can predispose to more severe disease if followed by infection by a different serotype. This means that instead of being protected, populations that have already experienced dengue infections can experience more severe disease and increase in deaths if a different dengue serotype is introduced into the population.

Permafrost

27One quarter of the northern Hemisphere is underlain by permafrost, a permanently frozen ground mostly present in Alaska, Canada, Greenland and Siberia, and in high mountain regions such as the Himalayas and the Alps. Above the permafrost lies an active layer (15 cm to 250 cm thick) that undergoes seasonal freeze-thaw cycles, while permafrost itself can reach depths of up to 1,500 meters deep.

  • 9 Swiss Federal Institute for Forest, Snow and Landscape Research WSL. (2024). Understanding the impa (...)

28Permafrost contains a wide range of microbial communities which remain stable due to the constant freeze. For example, as of today, up to 1,000 different microorganisms and hundreds of viruses were found in the Alpine permafrost and glacier ice. Yet, it is still unclear how these organisms survived, metabolized and even reproduced in such extreme conditions.9

  • 10 European Space Agency. (2021, October 26). Permafrost that could release bacteria and viruses. Euro (...)

29The rapid thawing of permafrost due to climate change poses unknown health risks, potentially releasing bacteria and unknown viruses. The temperature in the Arctic is warming twice as fast as in other areas, and projections suggest that up to two-thirds of the near-surface permafrost could disappear by 2100.10

30We live in a sea of microbes – in air, soil, water, in and on plants and animals. Most are not pathogenic for humans; many are essential for life as we know it. But microbes embedded in the permafrost or other inaccessible locations may have never been in contact with humans and might have novel virulence factors or toxins for which humans have no immunological experience.

  • 11 Often called an amoeboid, an amoebae is a type of cell or unicellular organism found in fungi, alga (...)
  • 12 Wu, R., Trubi, G., Tas, N., & Jansson, J. K. (2022). Permafrost as a potential pathogen reservoir. (...)

31Samples of Siberian soil, that had been frozen for 30,000 years, harbored two large DNA viruses that could infect amoebae.11 Other amoebae-infecting megaviruses dating back 48,500 years have also been unearthed.12 Additionally, over 100 microorganisms were found to be antibiotic resistant in Siberian permafrost.

  • 13 Cohen, J. (2023). Permafrost can imprison dangerous microbes for centuries. Will the Arctic thaw re (...)

32While the low population density of these areas lowers the likelihood of exposure and spread (less than 5 million people live on permafrost), communities living close to thawing sites may face increased risks, as animal carcasses or human remains are discovered. In Siberia for instance, in a particularly hot summer of 2016, 2,649 reindeers were killed and 36 people sickened by the Bacillus anthracis, the cause of anthrax.13 Scientists fear that it may have been released from the frozen ground. Although many uncertainties remain about the future impacts of thawing permafrost, the potential risks to human health warrant close monitoring and investment in scientific study of this unique ecosystem.

Interventions

  • 14 National Academies of Sciences, Engineering, and Medicine. (2022). Systematizing the One Health app (...)
  • 15 Hill, R., et al. (2024). Realizing a global One Health disease surveillance approach: insights from (...)

33The one health concept refers to the interconnectedness of humans, animals, plants, climate, and environment.14 Surveillance systems to detect microbial threats in humans and animals, including wildlife, should be systematic, global, and integrated. Surveillance for zoonotic viruses at animal-human interfaces should be strengthened, including in agricultural systems raising domestic animals. This means sampling birds and other wildlife, farm animals, agricultural workers, vectors, such as mosquitoes and ticks, and integrating it with data about human disease and outbreaks and with meteorological and other data.15

  • 16 National Academies of Sciences, Engineering, and Medicine. (2024). Increasing the utility of wastew (...)

34Wastewater provides vital health data as many pathogens or traces of them and chemicals enter the wastewater stream through saliva, urine and feces of people and animals. Wastewater monitoring has been used for decades to detect presence of polio virus in communities and guide vaccine use. Now, as part of a one-health surveillance system, it can serve as a valuable tool for detecting residues of antibiotics, presence of antibiotic resistance genes and fungal pathogens, and circulation of viruses in the community, such as SARS Co-V2 and mpox. Investigators are exploring its use in identifying new threats and mapping their spread, as rising levels of virus in wastewater often precede increased transmission in a community.16

35Social policies should aim to reduce spillover risks from wildlife to humans, such as by closing or strictly regulating commercial wildlife trade and markets.

36New tools, like field diagnostics and smart phones that can readily share data, have expanded the geographic reach and speed of communication. There are many examples of country, regional, and global systems that can contribute relevant data in realtime, including the Versatile Emerging Infections Observatory (VEO Forecasting) coordinated by Marion Koopmans (Netherlands); the CLIMADE, a consortium of scientists to develop tools to predict, track and control infections and develop ways to prevent epidemics; and the Global Virus Network. The GeoSentinel Global Surveillance Network systematically collects data on travelers worldwide (primarily after travel) as another way to identify infections linked to specific geographic exposures.

37The WHO Hub for Epidemic and Pandemic Intelligence, started in September 2021, focuses on Collaborative Surveillance, now a core element in WHO’s framework for global health emergency preparedness and response. Another key network is the Epidemic Intelligence from Open Sources. The platform now supports 94 Member States to enhance early detection capacity by connecting global experts. Despite these laudable efforts, many gaps remain in surveillance and response systems.

Conclusion

38Humans have created a world with more opportunities for connections – for contact across species and for rapid dispersal of microbes.

39Climate change will shift distribution of some vectorborne infections to expose even larger human populations. Climate change will lead to range shift of species allowing novel interactions and increasing the likelihood of spillover events. Shifts in migratory patterns of birds and other animals to achieve synchrony with food sources that shift with climate change, may also allow novel interactions among species. Waterborne- and food-associated infections, discussed later in this review, will likely increase with a warming climate.

40Climate change occurs in concert with multiple other profound, global changes that may exacerbate spillover events. These include changes in land use (cleared for agriculture or other development), travel, trade and migration, and loss of biodiversity making ecosystems more vulnerable to invasive species. Local events can now quickly become global.

41Most pandemics originate in animals. Global surveillance systems must include domestic animals and wildlife; vectors, such as mosquitoes; environmental reservoirs; and human populations. Better education and policies to regulate animal markets and wildlife trade can help reduce one area of risk. Although the one-health approach and new tools and communication networks show promise, much more needs to be done to limit the health consequences of climate change.

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Notes

1 Plowright, R.K., et al. (2017) Pathways to zoonotic spillover. Nature Rev Microbiol 15(August):502-510. www.nature.com/nrmicro.

2 Carlson, C. J., Albery, G. F., Merow, C., et al. (2022). Climate change increases cross-species viral transmission risk. Nature, 607(7919), 555–562. https://doi.org/10.1038/s41586-022-04788-w.

3 Mora, C., McKenzie, T., Gaw, I.M., et al. (2022) Over half of known pathogenic diseases can be aggravated by climate change. Nature Climate Change, 12(9), 869–875. https://doi.org/10.1038/s41558-022-01426-1.

4 de Souza, W.M. &, Weaver, S.C. (2024) Effects of climate change and human activities on vector-borne diseases. Nature Reviews Microbiology, 22(8), 476–491. https://doi.org/10.1038/s41579-024-01026-0.

5 Mordecai, E.A. et al. (2019) Thermal biology of mosquito-borne disease. Ecol Lett 22:1690-1708. Doi:10.1111/ele.13335.

6 Kuperschmidt, K. (2023) Feeling the heat. Science 2023;381(issue 6665):1388-92, p.1390.

7 de Souza, W.M. &, Weaver, S.C. (2024) Effects of climate change and human activities on vector-borne diseases. Nature Reviews Microbiology, 22(8), 476–491. https://doi.org/10.1038/s41579-024-01026-0.

8 Mordecai, E.A., et al. Ryan, S.J., Caldwell, J.M. Shah, M.M., LeBeaud, A.D. (2020) Climate change could shift disease burden from malaria to arboviruses in Africa. Lancet Planet Health 4:e416-23. www.thelancet.com/planetary-health.

9 Swiss Federal Institute for Forest, Snow and Landscape Research WSL. (2024). Understanding the impacts of climate change on Arctic, Antarctic, and Alpine permafrost microbiomes. https://www.wsl.ch/en/projects/einfluss-des-klimawandels-auf-das-permafrostmikrobiom-cryolink/.

10 European Space Agency. (2021, October 26). Permafrost that could release bacteria and viruses. European Space Agency. https://eo4society.esa.int/news/permafrost-thaw-could-release-bacteria-and-viruses/​:contentReference[oaicite:0]{index=0}​:contentReference[oaicite:1]{index=1}.

11 Often called an amoeboid, an amoebae is a type of cell or unicellular organism found in fungi, algae and animals.

12 Wu, R., Trubi, G., Tas, N., & Jansson, J. K. (2022). Permafrost as a potential pathogen reservoir. One Earth, 5(4), 351–360. https://doi.org/10.1016/j.oneear.2022.03.010.

13 Cohen, J. (2023). Permafrost can imprison dangerous microbes for centuries. Will the Arctic thaw release them? Science.org. https://www.science.org/content/article/permafrost-can-imprison-dangerous-microbescenturies-will-arctic-thaw-release-them#.

14 National Academies of Sciences, Engineering, and Medicine. (2022). Systematizing the One Health approach in preparedness and response efforts for infectious disease outbreaks: Proceedings of a workshop. The National Academies Press. https://doi.org/10.17226/26301.

15 Hill, R., et al. (2024). Realizing a global One Health disease surveillance approach: insights from wastewater and beyond. Nature Comm 15:5324. https://doi.org/10.1038/s41467-024-49417-4.

16 National Academies of Sciences, Engineering, and Medicine. (2024). Increasing the utility of wastewater-based disease surveillance for public health action: A Phase 2 report. The National Academies Press. https://doi.org/10.17226/27516.

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List of illustrations

URL http://journals.openedition.org/factsreports/docannexe/image/7727/img-1.jpg
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URL http://journals.openedition.org/factsreports/docannexe/image/7727/img-2.jpg
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Title Figure 1: Optimal temperature ranges for mosquito-borne diseases by disease-vector combination
Credits Source: Kuperschmidt, K., 2023
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Title Figure 2: Potential impacts of climate change on the geographical distribution of vectors
Credits Source: de Souza et al., 2024
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References

Bibliographical reference

Mary E. Wilson, “Spillover: From climate change to pandemics”Field Actions Science Reports, Special Issue 27 | 2025, 58-64.

Electronic reference

Mary E. Wilson, “Spillover: From climate change to pandemics”Field Actions Science Reports [Online], Special Issue 27 | 2025, Online since 15 December 2024, connection on 13 February 2025. URL: http://journals.openedition.org/factsreports/7727

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About the author

Mary E. Wilson

Clinical Professor of Epidemiology and Biostatistics at the School of Medicine of the University of California, San Francisco, and Adjunct Professor of Global Health and Population of the Harvard T.H. Chan School of Public Health in Boston

Mary E. Wilson, MD, is Clinical Professor of Epidemiology and Biostatistics at the School of Medicine of the University of California, San Francisco, and Adjunct Professor of Global Health and Population of the Harvard T.H. Chan School of Public Health in Boston, Massachusetts. Her academic interests include antibiotic resistance, the ecology of infections and emergence of microbial threats, travel medicine, tuberculosis, and vaccines. She is author of A World Guide to Infections: Diseases, Distribution, Diagnosis and Antibiotics: What Everyone Needs to Know, both published by Oxford University Press.

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Copyright

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The text only may be used under licence CC BY 4.0. All other elements (illustrations, imported files) are “All rights reserved”, unless otherwise stated.

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