Climate change and One Health

Abstract The journal The Lancet recently published a countdown on health and climate change. Attention was focused solely on humans. However, animals, including wildlife, livestock and pets, may also be impacted by climate change. Complementary to the high relevance of awareness rising for protecting humans against climate change, here we present a One Health approach, which aims at the simultaneous protection of humans, animals and the environment from climate change impacts (climate change adaptation). We postulate that integrated approaches save human and animal lives and reduce costs when compared to public and animal health sectors working separately. A One Health approach to climate change adaptation may significantly contribute to food security with emphasis on animal source foods, extensive livestock systems, particularly ruminant livestock, environmental sanitation, and steps towards regional and global integrated syndromic surveillance and response systems. The cost of outbreaks of emerging vector-borne zoonotic pathogens may be much lower if they are detected early in the vector or in livestock rather than later in humans. Therefore, integrated community-based surveillance of zoonoses is a promising avenue to reduce health effects of climate change.


INTRODUCTION
The journal The Lancet recently published a countdown on health and climate change to track the effects of mitigating climate change on public health (Watts et al. 2017). It provides an extensive plan on the reduction of greenhouse gas emissions and the reduction of climate change. However, the paper focuses on human public health effects of climate change alone, neglecting the important animal and environmental health. Addressing the effects of climate change and climate variability on health in concert illustrates the difficulty to disentangle them from numerous other phenomena of global change. Climate change is superposed by demographic, social and economic, environmental and landscape changes (Hwang et al. 2017) which often cannot clearly be separately delineated (de Anda 2017). Modifications in vector, reservoir and pathogen lifecycles as well as diseases of domestic and wild animals and plants are influenced by multiple complex processes (Semenza and Suk 2017). This also applies to the disruption of synchrony between interacting species, trophic cascades and alteration or destruction of habitats (Patz and Hahn 2013;Stevenson et al. 2015).
Consequently, we argue that the ecosystem approaches to health framework, which recognize the inextricable linkage of humans, animals and their environment and social context (Forget and Lebel 2001;Charron 2012;Martin-Diaz et al. 2017) or health in social-ecological systems (Zinsstag et al. 2011) would offer a more comprehensive and broader context to address the effect of climate change on health.
Apart from the above broader concept, we present a framework to complement The Lancet Countdown and extend the conceptual thinking to animal health, assessing the effects of climate change on what we call One Health, an integrated view of health of humans, animals and plants (Zinsstag et al. 2005(Zinsstag et al. , 2015Blaha 2012;Patz and Hahn 2013). In this paper, we limit our analysis to One Health and do not address climate change mitigation, which is well outlined by (Watts et al. 2017). The aim of this review is to (i) demonstrate advantages of integrated One Health approaches compared to conventional separated public and animal health approaches and (ii) examine the potential of One Health to adaptation to effects of climate change.

ONE HEALTH
We define One Health as any added value in terms of human and animal lives saved, reduced cost and sustained social and environmental services that can be achieved by a closer cooperation of human and animal health and other disciplines which could not be achieved if the sectors worked separately (Zinsstag 2015) ( Table 1). For example, joint human and animal vaccination services for mobile pastoralists provide access to health care for populations which would otherwise be excluded and saves fi-nancial resources while sharing the cold chain and transport costs between human and animal health services . As an example for a One Health approach to zoonoses control, it could be demonstrated that the benefits of brucellosis control for public health in Mongolia alone would not justify the cost of mass vaccination of livestock to prevent human brucellosis. But if all benefits of livestock brucellosis vaccination in the health and agricultural sectors are summed up, the societal benefits of livestock mass vaccination are three times higher than the intervention cost (Roth et al. 2003). Likewise, the annual cost of human post-exposure prophylaxis (PEP) from dog rabies is less than the cost of dog mass vaccination. However, the cumulative cost of dog mass vaccination with PEP is equal to the cumulative cost of PEP alone after 10 years as long as rabies is not re-introduced ( Fig. 1) Mindekem et al. 2017). Savings can also be achieved from shared infrastructure. The World Bank estimates a saving of 26% of the operations cost of the Canadian Science Centre in Winnipeg, hosting laboratories for human and animal highly contagious diseases under one roof (World-Bank 2012). The recent outbreak of Q-fever in the Netherlands with several thousand human cases could probably have been largely avoided if the veterinary and public health authorities had maintained continuous communication (Enserink 2010). Conversely, the integrated animal and human surveillance of West Nile Virus (WNV) in Emilia Romagna, Italy, shows savings of more than one million Euro, as compared to separate sectorial disease surveillance (Paternoster et al. 2017).
Similar savings have not yet been assessed but can be expected from food-borne zoonoses like salmonellosis and campylobacteriosis. Campylobacteriosis is one of the most important bacterial food-borne illnesses in humans caused, among others, through infection via handling and consumption of poultry meat. It is attributable to more than half of the Swiss winter peak of acute gastroenteritis (Bless et al. 2014) and for 40% of human campylobacteriosis cases in Belgium incurring over 10 million Euros annually of health care costs each in Belgium and Switzerland (Gellynck et al. 2008;Schmutz et al. 2017). Lowering Campylobacter spp. contamination of fresh poultry meat is feasible and cost-effective and has significantly reduced notifications of campylobacteriosis (by 52%) and hospitalizations for Guillain-Barré syndrome (by 13%) in New Zealand (Baker et al. 2012). In the following we examine the potential of such synergistic benefits of a closer cooperation of human and animal health to adapt to the effects of climate change.

CLIMATE CHANGE
Unequivocally, there is a warming of planet Earth since the 1950s, with increased temperatures of the atmosphere and the oceans. The amount of ice and snow has diminished; sea levels have risen; and an increased frequency of extreme weather Table 1. Examples of added value of One Health compared to separated human and animal health approaches.

Domain
Added value Reference Health services Joint human and animal vaccination services for mobile pastoralists provide access to health care for populations which would otherwise be excluded and save financial resources. Schelling et al. (2005) Zoonoses control Mass vaccination of livestock against brucellosis does not only benefit public health, but is three times more profitable from a societal perspective. Roth et al. (2003) Dog mass vaccination and human post-exposure prophylaxis is less costly than human post-exposure prophylaxis after 10 years Zinsstag et al. (2009);Mindekem et al. (2017) Surveillance and response Integrated surveillance and response of West Nile Virus saves more than one million Euro compared to separate human and animal surveillance.
Paternoster et al. (2017) Infrastructure The Canadian Science Centre in Winnipeg, hosting laboratories under one roof for highly contagious diseases affecting humans and animals alike saves 26% of the operations cost, compared to two separate human and animal health laboratories.
World-Bank (2012) Communication The recent outbreak of Q-fever in the Netherlands with several thousand human cases could probably have been largely avoided if the veterinary and public health authorities had maintained continuous communication. events, heat waves, drought, floods, storms are observed in parallel to an increase of the concentration of greenhouse gases (IPCC 2014). Climate change affects a large number of sectors. This means that integrated approaches and intersectoral collaboration are essential to face such challenges. The authors restrict this analysis to the added value of One Health approaches to adapt to health effects of climate change.

REVIEW METHOD
The purpose of this minireview is to propose novel conceptual thinking on integrated approaches for health of humans, animals and plants in relation to climate change. For this review, we initially tested the search strategy by considering the public databases of peer-reviewed literature included by Web of Science and PubMed from 2007 to date using keyword algorithms because One Health was not a recognized MESH term. Using a topic search, in Web of Science 1452 hits were returned while in PubMed 1070 hits were returned. Restricting the search field to title/abstract was possible in the PubMed database but not in Web of Science. Within the scope of our minireview, we deemed that sufficiently relevant publications should at least mention the keywords in the abstracts. Thus, we used the terms 'climate change' AND 'One Health' in the PubMed database with the search restricted to title/abstract in the timeframe from 2012 until 3 November 2017. We selected the time frame assuming that climate change and One Health as related topics were likely addressed only in the last decade. A test search expanding the time frame to the last 15 years returned exactly the same results. From 38 results, 35 were included following abstract review. One was excluded because no abstract was available, one was excluded as irrelevant because it investigated an extreme bush fire event and there was one duplicate. Twenty-nine full texts were freely available and included (see onlineAppendix). The gathered information from the relevant papers was scrutinized for topics and issues related to climate change that do or would benefit from integrated approaches to health and from which an added value of a closer cooperation of human and animal health could be expected, based on our previous experience as outlined above. In the selected papers, the topics of food security and safety and extensive livestock systems and pastoralism were found prominently cited in relation to climate change, environmental sanitation appeared as a further topic of the interaction of climate change and One Health followed by the potential of integrated surveillance and response systems in relation to climate change-related emerging diseases. These themes are clearly not exhaustive, and further potential of One Health to mitigate the effects of the changing climate can be expected in the near future.

THE ADDED VALUE OF ONE HEALTH TO CLIMATE CHANGE ADAPTATION
Complementary to The Lancet Countdown on climate change (Watts et al. 2017), a One Health approach to climate change, without being exhaustive, may significantly contribute to the following contexts and issues: food security with particular emphasis on animal source foods, extensive livestock systems, especially the role of ruminant livestock, antimicrobial resistance control, environmental sanitation, and steps towards regional and global integrated syndromic surveillance and response systems. Arctic regions appeared as highly vulnerable to zoonotic disease (Dudley et al. 2015;Ruscio et al. 2015), although other geographic regions like drylands and mountains are also hotspots of climate change.

FOOD SECURITY AND FOOD SAFETY
Food security is addressed by The Lancet Countdown from a public health perspective but does not address ecological sustainability of food security (Batsukh et al. 2013). In semi-arid and highland areas, people require livestock for livelihoods and food security, using both fresh and transformed animal source foods (Jans, Mulwa Kaindi and Meile 2016). Black and Butler (2014) refer to the complex nature of climate change and food security and integrated approaches to health which could lead to a new theory of health as an outcome of social-ecological systems (Zinsstag et al. 2011). In our experience in North Mali, Chad and the Ethiopian Somali Regional State droughts affect not only humans but often kill significantly more livestock than humans with catastrophic consequences not only in milk-based dietary systems . In many communities, minor disturbances in livestock strongly affect accessibility and availability of animal source foods, thereby decreasing opportunities for a diversified and nutritious diet and hence increasing the risk of malnutrition (FAO 2011). Observations of cereal and livestock prices are crucial for early detection of hunger crises (Bechir 2010). Heat stress affects many animals and food crops, reducing performance, growth and yield and likely also leading to increased animal mortality (Daramola, Abioja and Onagbesan 2012;Fahad et al. 2017). Conversely, climate change in temperate zones increases the vegetation period. However, to effectively translate prolonged vegetative periods into production growth, significant changes in agricultural systems and practices are required (FAO 2016).

EXTENSIVE LIVESTOCK SYSTEMS
The effect of methane production from rumination on climate change is known (Watts et al. 2017). A broader examination of this issue reveals that the ongoing increase of livestock production in the developing world elevates millions of small scale farmers out of the poverty trap (FAO 2011). At the same time, enormous increases in meat consumption in emerging middle classes in low and middle income countries contribute, albeit not exclusively, to an epidemiological transition and double burden of communicable and non-communicable diseases (Boutayeb 2006). As mentioned above, large areas of the world, for instance, semi-arid high and lowlands, could not sustain human life without use of livestock (Zinsstag et al. 2016). Climate change with increased droughts requires a high flexibility of mobile pastoralists and may lead to increased social conflicts when they must move into areas used by others (Herrero et al. 2016). An integrated societal view on global livestock production argues that ruminant livestock rearing should, within the limits of capacity of such social-ecological systems, be concentrated in semi-arid areas which cannot be used otherwise. In parallel, ruminant feedlot production would be stabilized or even decreased to reduce the climate impact of ruminant livestock and reserve substantial cereal food resources for human consumption. Altogether, a stabilization or reduction of global ruminant meat consumption seems inevitable and may have additional positive health effects.

INTEGRATED APPROACHES TO SAFE WATER, ENVIRONMENTAL SANITATION AND HYGIENE
Water, sanitation and hygiene (WASH) is an essential component of public health and of the One Health approach. Inappropriate animal and human excreta management can both contribute to the pollution of the environment (e.g. water and soils) and the spread of antimicrobial resistance and hence need to be managed jointly. Climate change leads to more frequent periods of high precipitation causing an excess in runoff and associated wash-off of human and animal feces containing zoonotic pathogens from manure-fertilized fields or open defecation to surface and drinking water sources will potentially increase the risk of disease outbreaks (Sterk et al. 2013(Sterk et al. , 2016. Increased extreme events such as hurricanes and flooding, for example, have been associated with the emergence of leptospirosis that necessitates close study of the animal reservoirs (Mwachui et al.  (Flutsch et al. 2008). This has also been shown for cryptosporidiosis and giardia in Africa (Squire and Ryan 2017). The link between climate change and diarrhea, a very sensitive disease to environmental sanitation conditions, has been highlighted in a number of recent studies (Thiam et al. 2017). Water and sanitation systems are very much sensitive to climate change extreme events, with particular challenges in urban contexts (Sherpa et al. 2014;Cissé et al. 2016). Climate warming also may lead to increased occurrence and relevance of non-cholera vibriosis in humans (Huehn et al. 2014). Pollution of riverbank sediments should be considered as an early warning sign for human and animal health, notably also in regard to coastal seafood production (Martin-Diaz et al. 2017). Safe procedures of integrated animal and human excrement recycling may reduce zoonotic disease risk and maintain valuable limited nutrient resources for food production (Nguyen-Viet et al. 2009;Dahal, Upadhyay and Ewald 2017). Such procedures include the composting of human and animal excreta (Zhang et al. 2014;Vu-Van et al. 2017). New double vault composting latrines reduce the number of viable Ascaris suum eggs and provide hygienically acceptable fertilizer (Jensen et al. 2009). Besides infectious diseases, further risk arises from high levels of mercury and persistent organic pollutants circulating within terrestrial and aquatic ecosystems which are a major concern for the reproductive health of humans (Dudley et al. 2015). Many sectors (particularly agriculture, water and health) are very much interconnected. Many African states cannot afford allocating to any of these sectors sufficient resources to achieve, for example, their related targets for Sustainable Development Goals. In that context, the challenges of climate change in environmental sanitation sector are huge, and integrated approaches, like the reduction of open defecation or low cost water cleaning beds while producing animal feed, can contribute a lot in facing these, particularly in Africa . Experts from the different sectors could work together in the elaboration of evidencebased sanitation safety plans (WHO 2015). The wider consideration of integrated approaches could bring the sectors working much closely together particularly in the domain of safety of water, integrated environmental sanitation and hygiene at different levels. The integrated management entails proper water protection, efficient waste treatment methods (at the household and community levels) including tailored safe recovery, recycling, and reuse of both human and animal excreta, designing appropriate technologies, setting relevant policies and promoting hygiene in the different contexts. More specifically, a number of interventions are recommended to reduce the exposure of humans to animal feces, e.g. proper disposing of both animal feces, creating safe child spaces in households, reducing cohabitation with animals, controlling animal movements, and promoting handwashing and domestic environment hygiene (Penakalapati et al. 2017). Transdisciplinary approaches, engaging scientists with communities and authorities, are proposed for sustainable problem solving (Ruscio et al. 2015), and such approaches are an integral part of One Health (Schelling et al. 2007;Zinsstag 2015).

TOWARDS REGIONAL AND GLOBAL INTEGRATED SURVEILLANCE-RESPONSE SYSTEMS
Integrated human and animal surveillance and response systems (iSRS) are one of the most important contributions of a One Health approach to mitigate effects of climate change. While public health surveillance is restricted to humans, understanding vector-borne diseases and climate change per se call for an integrated One Health approach (Semenza and Zeller 2014;Elbers, Koenraadt and Meiswinkel 2015). The above-mentioned example of integrated WNV surveillance in mosquitos, birds, horses and humans is a case in point (Paternoster et al. 2017). The World Bank makes a compelling case for integrated human and animal surveillance (Fig. 2), emphasizing that if emerging diseases can already be detected in vectors, livestock or wildlife, prior to detection in humans, very large costs could be averted (World-Bank 2012; Heymann and Dixon 2013). Savings of 344 to 360 billion USD over the next 100 years are expected from use of integrated surveillance of zoonoses with a pandemic potential (Pike et al. 2014). Savings from early detection of pathogens in vectors would not only apply to vector-borne zoonoses but also for vector-transmitted diseases like dengue fever (Li and Wu 2015).
Unfortunately, public and animal health surveillance systems often fail to communicate. For example, an outbreak of Rift Valley fever (RVF) in Mauritania was mistaken for yellow fever and detected only after communication with the veterinary services who observed abortions due to RVF in livestock (Digoutte 1999). Febrile illness in Bamako, Mali, is most often associated with malaria, ignoring the importance of zoonotic diseases like brucellosis or Q-fever (Steinmann et al. 2005). Similarly, the Dutch public health authorities complained that more than 3000 cases of human Q-fever could have been prevented if the veterinary services had communicated a large outbreak in goats (Enserink 2010). It makes a lot of sense that the surveillance of vector-borne zoonoses is coupled between entomological, animal and human surveillance systems, e.g. for Japanese encephalitis virus in China (Baylis et al. 2016), borreliosis in Serbia (Savic et al. 2014) or West Nile Fever in Europe (Gossner et al. 2017). Such iSRS should also include terrestrial wildlife (Singh and Gajadhar 2014) and marine animals (Stephen 2014). The importance of including wildlife in iSRS is further demonstrated by the example of blood transcriptomes in lemurs that reveal novel parasitic zoonoses in Madacascar (Larsen et al. 2016). In South Korea, migration of wildlife, international human movement and illegal importation of wildlife were identified as the main risks for pathogen introduction into the country (Hwang et al. 2017). Individual countries like Mongolia are currently developing One Health iSRS systems (Batsukh et al. 2013), while others are proposed (Cheng, Mantovani and Frazzoli 2017).
In addition to integration of human and animal disease surveillance, modern communication technologies (Seid et al. 2016) used at the community level will provide the highest surveillance sensitivity and be instrumental in reducing time to detection and hastening etiological confirmation of pathogens responsible for outbreaks. Mobile technologies, in particular, can assist in the early detection of zoonoses and provide the opportunity to intervene before a few infections can turn into an epidemic. With mobile devices such as smartphones, relevant data can be collected and analyzed in near real time. These new opportunities have led to the emergence of infodemiology (Eysenbach 2011), a new discipline within public health informatics which includes applications such as the capturing of critical incidents regarding animal and human health to predict disease outbreaks, monitoring and tracking them for syndromic surveillance and sending alerts to the appropriate health authorities (Jean-Richard et al. 2014;Toda et al. 2017). Social media platforms also serve as novel sources of rich observational data for health research including infodemiology. However, the challenge often does not lie in the availability of relevant information, but in its aggregation and analysis. For this purpose, standards of reporting data sources and quality are needed so that data scientists and One Health experts can evaluate and compare methods and findings across studies and sectors (Schelling and Hattendorf 2015;Kim, Huang and Emery 2016).
Control and elimination of many zoonoses requires regional coordination to avoid re-introduction and to plan effective strategies for sustainable elimination. For example, bioregional approaches are proposed between Mexico and the USA (Pezzoli et al. 2014) and between the countries of the former Soviet Union (Bartholomew et al. 2015). Regional initiatives like the European Early Warning and Response System (EWRS, https://ewrs.ecdc.europa.eu/accessed 31 December 2017) would have the potential to be cross linked with animal disease surveillance. Global initiatives like the Global Outbreak Alert and Response Network (GOARN) http://www.who.int/ihr/alert and response/outbreak-network/ en/ currently concentrate only on public health institutions, but the joint FAO-OIE-WHO Global early warning system for health threats and emerging risks at the human-animal-ecosystems interface (GLEWS www.glews.net) is a truly integrated global iSRS.

ONE HEALTH EDUCATION
One Health approaches show clear advantages over conventional public and animal health approaches not only for adaptation to and mitigation of climate change (Shomaker, Green and Yandow 2013), but also for surveillance of antimicrobial resistance and many non-communicable diseases. A main problem is lack of intersectoral collaboration, and particularly between the medical and veterinary communities, perhaps due to already full curricula with little time for adding integrated courses, despite evidence for the higher cost of overspecialization and lack of communication between sectors (Enserink 2010). There is an urgent need to include One Health meaningfully into medical and veterinary curricula (Rabinowitz et al. 2017), and the first massive open access online course already exists (www.futurelearn.com/courses/one-health accessed 31 December 2017). And (www.coursera.org/learn/globalhealth-human-animal-ecosystem accessed 31 December 2017). There is no need for new ministries or academic institutions if people are well trained and informed. Existing legal systems are adequate to regulate professional services in all sectors, but mechanisms to work better together and to communicate fully between the involved sectors of human health, animal health and environmental heath are of high priority (Videla and Urzua 2014).

CONCLUSION
Here we presented an account of the unmatched value of a One Health approach over the conventional public health approach. Its advantages go beyond human and animal health. One Health is well suited for community-based contextual problem solving through transdisciplinary processes. It is this aspect of One Health which suggests the groundbreaking directions in the pursuit of high networking of different disciplines and that garnered the attention of both scientific and non-scientific communities. In the case of climate change, integrated One Health approach offers societally meaningful collaborative efforts to reconcile scientific disciplines, policy making and local knowledge by engaging non-academic stakeholders and different academic disciplines to act together locally, nationally and globally to address and solve health problems related to climate change.

SUPPLEMENTARY DATA
Supplementary data are available at FEMSLE online.

FUNDING
This work has been supported by the Swiss Agency for Development and Cooperation JOHI and PADS projects, the Swiss National Science Foundation r4d project in Guatemala, the Swiss Universities SUDAC-COFER program and Afrique One Aspire.