through transmission of zoonotic diseases or loss of animals for ploughing. Large parts of the world could not be inhabited without the use of livestock in a moderate way. Consequently, we can no longer close our eyes to the close linkage, interrelations and interdependencies of human and animal health without considering simultaneously maintenance of stable ecosystem services, some of which are seriously threatened by livestock rearing methods and/or excessive human exploitive activities.
Peter Rabinowitz, an occupational physician at Yale University proposed that humans should change their point of view towards animals from an ‘us versus them’ to a ‘shared risk’ attitude between humans and animals (Rabinowitz et al., 2008; Rabinowitz and Conti, 2010). As an example, we can consider the high cancer rate of beluga whales in the Saguenay Fjord in Canada. Belugas are continually exposed to industrial and other human-derived wastes. The beluga cancer incidence has become an indicator of environmental quality. Humans therefore have an interest in preserving the quality of the environment in a state that does not adversely affect both whale and human health.
From an integrative One Health, conservation biology and/or an ecosystem perspective, animals should be much better valued and treated as part of an overall effort to maintain and sustain ecosystem integrity and, thus, comprehensive well-being. This involves, among other things, animal husbandry and rearing, animal transport, slaughter practices, animal traction and wildlife conservation (see White et al., Chapter 3, this volume; Bunch and Waltner-Toews, Chapter 4, this volume; Wettlaufer et al., Chapter 11, this volume).
Globally, most livestock holders treat their animals well. In Fig. 2.2 we observe a nearly unrestrained type of animal husbandry. The horse being milked by the Kyrgyz lady stands still without being tied. Similarly, the camels and donkeys in Ethiopia are calm and obviously well treated. However, animal welfare is clearly insufficient in semi-intensive and intensive production systems. Livestock holders should be continuously trained on best animal welfare practices in their rearing systems. From an animal welfare perspective, the current practice of transporting livestock on foot, say from Ireland to France for slaughter, is not acceptable. Similarly, in developing countries, small ruminants and poultry are transported hundreds of kilometres under congested conditions, often without water, and sometimes severely beaten. Slaughtering practices should aim to reduce stress during animal handling. As part of economic growth, meat consumption has grown massively in the last decades. Livestock plays an important role especially in the livelihoods of hundreds of millions of small-scale farmers. However, ruminant livestock production contributes to the emission of greenhouse gases, and reduction of ruminant meat consumption is part of the overall strategy to avert climate change (Gordon et al., Chapter 25, this volume).
Fig. 2.2. Camels and donkeys in Ethiopia (A) and a woman milking a horse in Kyrgyzstan (B). Photos courtesy of J. Zinsstag.
Animals are also, one might say mostly, used in agriculture in developing countries for ploughing, transport and traction of carriages. While cattle and camels used for ploughing or transport are usually well treated, there is undeniably huge suffering in horses and donkeys used for transport. Donkeys are among the worst-treated animals worldwide and urgently need better treatment and husbandry. There is increasing research on livestock, companion animals and wildlife in developing countries. However, there is almost a complete lack of legislation on animal testing. Care should be taken that animal testing is not exported from industrialized countries to evade stringent regulations. We should not forget the welfare standards for pets, which may similarly undergo huge suffering. For example, dogs and cats are often abandoned at the beginning of the summer holidays, so that owners do not have to care for them.
From a One Health perspective, the notion of burden of disease should be extended to animals to reflect the toll of life and suffering of humans and animals, for example in road traffic, which causes hundreds of thousands of wildlife deaths. Road safety should then be expressed as causing this number of human and this number of animal casualties. Modern highway planning effectively protects animal life by utilizing fencing, bridges and tunnels for safe animal movement. While animal lives can be counted, estimating animal suffering and disability, similarly to human burden measures like the disability adjusted life year (DALY), is hardly possible because of the variation of norms and values across cultures and production systems. For example, how would expected years of life for male calves or fattening pigs be adequately assessed? There is an ongoing and controversial debate, but still not enough research undertaken, in development of a combined metric of human and animal disease burden. The recent introduction of the zDALY, an adjusted indicator to estimate the burden of zoonotic diseases, is controversial because it puts a monetary value on human life depending on local purchasing power (Torgerson et al., 2018; Häsler et al., Chapter 10, this volume). Improving animal welfare remains a permanent challenge to any effort and ethical aspiration of One Health (Wettlaufer et al., Chapter 11, this volume).
One Health as embedded in landscapes
One Health as presented here is not an isolated idea. There are earlier more limited and also broader concepts. We should mention Evgeny Pavlovsky’s (1884–1965) concept of disease nidality. He considered pathogens from an ecological perspective having their own ecological niche. This might be a specific space in an ecosystem or an animal or organ to which they are most adapted. For example, marmots in Mongolia carry Yersinia pestis, the agent of plague, without symptoms. Occasionally, marmot hunters become ill with plague after handling marmot carcasses.
Calvin Schwabe met Evgeny Pavlovsky in Leningrad in 1965 and wrote in his memoirs:
The only noteworthy work-related event in Leningrad was my meeting with Eugene Pavlovsky, the dean of the Soviet descriptive epidemiologists, formal developer of medical ecological notions like ‘landscape epidemiology’ and ‘natural foci of infections’. … He had read Veterinary Medicine and Human Health [(Schwabe, 1984) reference added] already and said he was pleased to see an American author write on the ‘Ecological Study of Disease’, which was my title of the 1st edition chapter introducing epidemiology.
(C. Schwabe, unpublished)3
More recent examples of landscape–disease interactions include the ways in which emerging diseases, such as those associated with West Nile virus and Borrelia burgdorferi, are related to urban landscape design (Waltner-Toews and Waltner-Toews, 2017).
One of the most prominent interactions of human and animal health is veterinary public health (VPH), which is defined as the contribution of veterinary medicine to public health. VPH is well established in international organizations, governmental administrations and academia. VPH was originally conceived by the Centers for Disease Control in Atlanta by James H. Steele. Schwabe refers to it as ‘the innovative Veterinary Public Health Unit founded by Jim Steele, … helping to demonstrate the value of an organised and systematic capability for disease intelligence’ (C. Schwabe, unpublished)4.
Compared to One Health, VPH mainly serves public health. Conceptually, it does not consider a mutual benefit from public health for animal health.
A much broader concept is an ‘ecosystem approach to health’ or ‘ecohealth’. Ecohealth