key: cord-303197-hpbh4o77
authors: Humboldt-Dachroeden, Sarah; Rubin, Olivier; Frid-Nielsen, Snorre Sylvester
title: The state of one health research across disciplines and sectors – a bibliometric analysis
date: 2020-06-06
journal: One Health
DOI: 10.1016/j.onehlt.2020.100146
sha: 
doc_id: 303197
cord_uid: hpbh4o77

There is a growing interest in One Health, reflected by the rising number of publications relating to One Health literature, but also through zoonotic disease outbreaks becoming more frequent, such as Ebola, Zika virus and COVID-19. This paper uses bibliometric analysis to explore the state of One Health in academic literature, to visualise the characteristics and trends within the field through a network analysis of citation patterns and bibliographic links. The analysis focuses on publication trends, co-citation network of scientific journals, co-citation network of authors, and co-occurrence of keywords. The bibliometric analysis showed an increasing interest for One Health in academic research. However, it revealed some thematic and disciplinary shortcomings, in particular with respect to the inclusion of environmental themes and social science insights pertaining to the implementation of One Health policies. The analysis indicated that there is a need for more applicable approaches to strengthen intersectoral collaboration and knowledge sharing. Silos between the disciplines of human medicine, veterinary medicine and environment still persist. Engaging researchers with different expertise and disciplinary backgrounds will facilitate a more comprehensive perspective where the human-animal-environment interface is not researched as separate entities but as a coherent whole. Further, journals dedicated to One Health or interdisciplinary research provide scholars the possibility to publish multifaceted research. These journals are uniquely positioned to bridge between fields, strengthen interdisciplinary research and create room for social science approaches alongside of medical and natural sciences.

One Health joins the three interdependent sectors -animal health, human health, and ecosystems -with the goal to holistically address health issues such as zoonotic diseases or antimicrobial resistance (1) . In 2010, the Food and Agriculture Organization (FAO), the World Organisation for Animal Health (OIE) and the World Health Organization (WHO) engaged in a tripartite collaboration to ensure a multisectoral perspective to effectively manage and coordinate a One Health approach. One Health is defined as "an approach to address a health threat at the human-animal-environment interface based on collaboration, communication, and coordination across all relevant sectors and disciplines, with the ultimate goal of achieving optimal health outcomes for both people and animals; a One Health approach is applicable at the subnational, national, regional, and global level" (2). This paper uses bibliometric analysis to explore the state of One Health in academic literature, to visualise between the disciplines of human medicine, veterinary medicine and environment still persist -even in the face of the One Health approach.

The data for the bibliometric analysis is drawn from the Web of Science (WoS). The WoS is arguably one of the largest academic multidisciplinary databases, and it contains more than 66,9 million contributions from the natural sciences (Science Citation Index Expanded), social sciences (Social Sciences Citation Index) and humanities (Arts & Humanities Citation Index) (7). The broad scope of the database aligns well with the One Health concept's cross-disciplinary approach. The analytical period is demarcated by the first One Health publication included in the WoS in 1998 and it ends in December 2019. The search term "One Health" was applied to compile the first crude sample of articles that mention the concept of One Health in their title, keywords or abstract. The basic assumption is that articles conducting One Health research ( whether conceptually, methodologically and/or empirically) would as a minimum have mentioned "One Health" in the abstract, title or keywords. The literature search resulted in 2.004 English articles, see flow chart in figure 1. However, this sample also included a sizable group of articles that just made use of "one health" in a sentence such as "one health district" or "one health professional". To restrict the sample to contributions only pertaining to the concept of One Health, two subsequent screening measures were taken. First, 587 contributions which used One Health as a keyword were automatically included in the The bibliometric analysis was conducted with the bibliometrix package for the R programming language.

The analysis focuses on: 1) publication trends, 2) co-citation network of scientific journals, 3) co-citation network of authors, and 4) co-occurrence of keywords.

The publication trend is outlined using both absolute and relative number of One Health publications. The co-citation networks of scientific journals provide information on the disciplinary structure of the field of One Health while the co-citation network of authors disaggregates further to the citation patterns of individual authors. The co-citation network of journals shows the relation between the publications within the outlets. For example, when a publication within journal A cites publications within journals B and C, it indicates that journals B and C share similar characteristics. The more journals citing both B and C, the stronger their similarity. To minimise popularity bias among frequently cited journals, co-citation patterns are normalised through the Jaccard Index. The Jaccard Index measures the similarity between journals B and C as the intersection of journals citing both B and C, divided by the total number of journals that cited B and C individually (8, 9) . Like the co-citation network of journals, the co-citation network for authors measures the similarity of authors in terms of how often they are cited by other authors , also normalised through the Jaccard Index. When author A cites both authors B and C, it signifies that B and C share similar characteristics.

The study also investigates the co-occurrence of keywords to identify the content of One Health publications. Here, co-occurrence measures the similarity of keywords based on the number of times they occur together in different articles. It provides information on the main other topical keywords linked to One Health and can thus be used to gauge the knowledge structure of the field. Here, the articles Keywords Plus are the unit of analysis. WoS automatically generates Keywords Plus based on the words or phrases appearing most frequently in an articles bibliography. Keywords Plus are more fruitful for bibliometric analyses than author keywords, as they convey more general themes, methods and research techniques (10) .

Disciplinary clusters within the networks, illustrated by the colours in figures 3 to 5, are identified empirically applying the Louvain clustering algorithm. Louvain is a hierarchical clustering algorithm that attempts to maximise modularity, measured by the density of edges between nodes within communities and sparsity between nodes across communities. The nodes represent the aggregated citations of the academic journals and the edges, the line between two nodes, display the relation between the journals.

The shorter the path between the nodes the stronger their relation. Node size indicates "betweenness centrality" in the network, which is a measure of the number of shortest paths passing through each node (11) . Betweenness centrality estimates the importance of a node on the flow of information through the network, based on the assumption that information generally flows through the most direct communicative pathways. For example, the One Health publications in our sample relating to Ebola have more than tripled after 2016.

One might, therefore, expect to observe a similar spike in One Health publications that study the COVID-19 outbreak in 2020.

While the use of the One Health concept has increased, the co-citation network shows that the increase is mostly driven by the sectors of human and veterinary medicine, evidenced by their centrality in terms of information flows within the network. relations to other clusters. The area of parasitology is also mostly co-cited in its own area. Here, most aggregated citations are rooted in the journal PLOS Neglected Tropical Diseases. In these last two clusters, microbiology and parasitology, the journals cover topics mainly exclusively pertaining to medical or biological sciences.

The most active One Health scholars, publishing more than ten articles over the last 12 years, are from the field of veterinary research. Of the top six researchers, five have a veterinary background (Jakob Zinsstag, Jonathan Rushton, Esther Schelling, Barbara Häsler and Bassirou Bonfoh). While Degeling is the only researcher of the top six with an education in the social sciences, the remaining five veterinarian scholars do touch upon social science themes within their publications, relating to systemic or conceptual approaches, sociopolitical dimensions and knowledge integration (e.g. Zinsstag and Schelling (14) ; Häsler (15) ; Rushton (16) . Five of the six most productive researchers work in Europe and three of them are associated with the same institute, namely the Swiss Tropical and Public Health Institute (Zinsstag, Schelling and Bonfoh) (17) .There has been some cooperation across institutes and department as evidence by the coauthorships of Zinsstag and Häsler, Häsler and Rushton, Rushton and Zinsstag (e.g. (18) (19) (20) ). Figure 4 illustrates the co-citation network of authors. Four clusters of authors emerged in the network (green: zoonoses and epidemiology; blue: biodiversity and ecohealth; purple: animal health, public health; red: policy-related disciplines). Academic scholars are mainly found in the green, blue and purple clusters, whereas the authors of the red clusters are mainly represented by organisations such as the WHO, CDC, perspectives from the environmental and ecological sector have been neglected within One Health research (24, 25) . Further, the co-occurrence network of keywords illustrated that research into One Health is mainly undertaken in the medical science cluster with the most connections to the other clusters. This indicates that a majority of articles is constructed around medical themes, and that there is most interdisciplinary research across areas in the medical science cluster. However, few keywords indicate research into administrative or anthropological approaches to examine the management of One Health.

Making these thematic perspectives more central to the network could strengthen the One Health approach regarding implementation and institutionalisation. One Health initiatives and projects that specifically promote mixed methods studies and engage researchers with various expertise could facilitate implementing comprehensive initiatives. Here, a gap in the One Health research could be addressed, facilitating not only quantitative but a qualitative research to comprehensively approach the multifaceted issues implied in One Health topics (26) .

There is no shortage of existing outlets, frameworks and approaches that promote interdisciplinary research. Already in 2008, a strategic framework was developed by the tripartite collaborators, as well as the UN System Influenza Coordination, UNICEF and the World Bank, outlining approaches for collaboration, to prevent crises, to govern disease control and surveillance programmes (27) . Rüegg et al. developed a handbook to adapt, improve and optimise One Health activities could also provide some guidance on how to strengthen future One Health activities and evaluate already ongoing One Health initiatives (18) . Coker et al. produced a conceptual framework for One Health, which can be used to develop a strong research 

The FAO-OIE-WHO Collaboration -Sharing responsibilities and coordinating global activities to address health risks at the animal-human-ecosystems interfaces -A Tripartite Concept Note

Applied Informetrics for Digital Libraries: An Overview of Foundations, Problems and Current Approaches

Transdisciplinary and social-ecological health frameworks-Novel approaches to emerging parasitic and vector-borne diseases

Posthumanist critique and human health: how nonhumans (could) figure in public health research

Citation Index Is Not Critically Important to Veterinary Pathology

On the normalization and visualization of author co-citation data: Salton's Cosine versus the Jaccard index

Similarity measures in scientometric research: the Jaccard index versus Salton's cosine formula. Information Processing & Management

Comparing keywords plus of WOS and author keywords: A case study of patient adherence research

Fast unfolding of communities in large networks

Ebola Outbreak Distribution in West Africa

Ebola Virus Disease)

Reporting and Surveillance -Zika Virus

From "one medicine" to "one health" and systemic approaches to health and well-being

Knowledge integration in One Health policy formulation, implementation and evaluation

Towards a conceptual framework to support one-health research for policy on emerging zoonoses

Swiss TPH -Swiss Tropical and Public Health Institute

Integrated approaches to health: A handbook for the evaluation of One Health

A review of the metrics for One Health benefits

A Blueprint to Evaluate One Health. Front Public Health

Implementing a One Health approach to emerging infectious disease: reflections on the socio-political, ethical and legal dimensions

Overcoming challenges for designing and

A framework for One Health research. One Health

The growth and strategic functioning of One Health networks: a systematic analysis. The Lancet Planetary Health

Qualitative Research for One Health: From Methodological Principles to Impactful Applications. Front Vet Sci

Contributing to One World, One Health* -A Strategic Framework for Reducing Risks of Infectious Diseases at the Animal -Human-Ecosystems Interface

BIRDS OF A FEATHER: Homophily in Social Networks

Homophily in co-autorship networks