One Health Approach
Humans share the planet with a variety of animals and plants, and the health of all species is intertwined. Agriculture started 11 000 years ago, predisposing interactions between species and the evolution and transmission of pathogens. An estimate suggests that 77% of livestock pathogens can infect multiple host species; over half of all recognized human pathogens are currently or originally zoonotic, as are 60%-76% of recent emerging pathogens.Reference Wiethoelter, Beltrán-Alcrudo and Kock 1 , Reference Bernstein, Ando and Loch-Temzelides 2 According to the World Organization for Animal Health (WOAH), 3 more than 20% of global animal production losses are linked to animal diseases. The epidemics and pandemics such as influenza, cholera, mosquito-borne diseases (zika, chikungunya), Ebola, SARS-CoV-1, MERS, monkey pox, and in particular SARS-CoV-2 have necessitated adopting a systems approach based “One Health” to prevent, predict, prepare for, detect, and respond to global health threats. 4 The One Health approach aims to offer concrete solutions to cross-cutting issues of zoonoses, neglected tropical diseases, vector-borne diseases, antimicrobial resistance (AMR), food safety and food security, environmental pollution, climate change, and other health threats shared by people, animals, and the environment.
To enhance global action and operationalize One Health, the quadripartite agencies: the Food and Agriculture Organization of the United Nations (FAO), United Nations Environment Program (UNEP), World Health Organization (WHO), and WOAH (founded as OIE) established the interdisciplinary OHHLEP to support achieving national targets and enable learning and exchange across sectors. 5 Equity, sociopolitical and multicultural parity, socioecological equilibrium, stewardship, and transdisciplinarity are the key principles of the OHHLEP. As a call to action, the commitment has been scaled up to translate the One Health approach into actionable policies before 2026. In the recent G20 meeting,Reference Dasgupta 6 the One Health approach was reinforced to prioritize infection prevention and control, combat AMR, and lead in antimicrobial stewardship.
The recent developments in the One Health approach provide a vast opportunity for the One Health community to strengthen cross-sectoral collaboration and increase policy coordination and coherence through the application of a more systematic scientific classification and estimation of diseases ICD -11.
Discussion
ICD and Status of Global Estimates on Human Health and Disease Burden
The ICD 7 has been the basis for estimating and comparing morbidity and mortality statistics between geographies over time. Originating in the 19th century, the revised version of ICD-11 was adopted by the 72nd World Health Assembly in 2019. It became effective on January 1, 2022, and allows countries to count and identify their most pressing health issues by using an up-to-date and clinically relevant classification system.
Characteristics of ICD-11
The clinical terms are coded based on the latest medical and scientific knowledge. There are 17 000 diagnostic categories with over 100 000 medical diagnostic index terms. The index-based search algorithm interprets more than 1.6 million terms.
Purposes and uses of ICD-11
The purposes of ICD are systematic recording, analysis, interpretation, and comparison of morbidity and mortality data; trending the health of the population; diagnostic guidance; and monitoring for epidemics and pandemics. Thus, ensuring semantic interoperability and reusability of recorded data for different uses goes beyond mere health statistics and research. The information gathered through ICD provides governments with the ability to design effective public health policies and measure their impact. A few specific uses of ICD-11 are briefly stated below:
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a) AMR: The ICD provides the details recommended by the WHO’s Global Antimicrobial Resistance and Use Surveillance System (GLASS) 8 that enable the recording and reporting of the infection, the pathogen, and the level and type of resistance to specific drugs for antimicrobial stewardship.
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b) There are over 200 known zoonotic diseases, yet a few are coded in ICD-11. The codes for certain zoonotic diseases are categorized under certain infectious or parasitic diseases as “01.” The codes for certain zoonotic bacterial diseases begin with “1B9” and list 12 diseases. The codes for certain zoonotic viral diseases begin with “1D6” and list 8 diseases. COVID-19 has a code of “RA01.0.” Influenza due to an identified zoonotic or pandemic influenza virus has a code of “1E31.” Influenza, a virus not identified, has a code of “1E32.” Rabies has a code of “IC82.” Twenty-five codes have been given for special purposes, i.e., international, and national provisional assignment of new diseases of uncertain etiology and emergency use; and an unspecified infection has a code of “1H0Z.” However, there are no matching entities in the ICD-11 coding tool for the simple search or flexible search for “zoonoses.”
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c) WHO’s global health estimates (GHE): The most recent data are extracted from multiple sources using ICD on causes of disability and death globally by WHO region and country, categorized by socio-demographic variables. The estimates released in 2020 report on trends for more than 160 diseases and injuries annually from 2000-2019. 9
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d) Morbidity coding and reporting: Precise information on what people fall sick from and are treated for is recorded and reported with ICD. This information serves policy design, planning, and monitoring the health of a population.
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e) Estimating causes of death: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) quantifies global health by estimating key demographic metrics and comprehensive health metrics for a set of national and subnational locations to support prevention, evaluation of programs, and investments in human health. In accordance with ICD principles, codes, and WHO, the Institute for Health Metrics and Evaluation’s (IHME) GBDReference Dattani, Spooner and Ritchie 10 has developed a standardized approach to the attribution of deaths: “each death is attributed to a single underlying cause that initiated the series of events leading to death.”
Status of Global Estimates on Animal Health and Disease Burden
Animal health has major impacts on human health, either through zoonotic disease transmission or through nutritional supplies and environmental governance. To implement the One Health approach, a consistent and comparable estimate of animal diseases and their effect on human health is important.
The World Animal Health Information System (WAHIS) - the global animal health reference database
Estimating animal health and the burden of diseases (morbidity and mortality) is carried out by extracting data from FAO (FAOSTAT and Empress-I – global animal disease information system), Eurostat, and WOAH (WAHIS). Since 2005, WAHISReference Caceres, Awada and Weber-Vintzel 11 has gathered information from the 182 member countries, non-members, and territories on terrestrial and aquatic listed diseases in domestic animals and wildlife, including emerging diseases and zoonoses. Of the 230 terrestrial and aquatic animal diseases listed, 120 are reportable, 15 are emerging reportable, and 6 are selected or reportable for trade purposes, whereas 54 are not listed among wildlife.
The Global Burden of Animal Diseases (GBADs) and the gaps in estimates of animal health and disease burden
The prevailing practice of animal health estimates is inherently fragmented. Accurate livestock numbers are an essential input for estimating measures of morbidity and mortality and antimicrobial use that have an impact at local, national, and global levels. Underreporting of diseases, including zoonoses, mostly from low-income settings leads to an underestimation of the burden of diseases.Reference Rushton, Bruce and Bellet 12
The Global Burden of Animal Diseases (GBADs)Reference Raymond, BenSassi and Patterson 13 , 14 program of the WOAH is in its infancy and has a limited understanding of the problem. The availability and quality of the data represent a challenge. The numbers and categorization of animals are not consistent across different organizations or over time: sheep and goats are sometimes combined as small ruminants, and cattle may or may not include buffaloes or be divided into beef and dairy. The coding attributes of ICD-11 on morbidity, mortality, and zoonoses don’t exist in WAHIS. On the other hand, the terrestrial and aquatic animal health codes in WOAH mean measures for the prevention, early detection, reporting, and control of pathogens, including zoonoses, in terrestrial animals (mammals, reptiles, birds, and bees), besides ensuring the safety of international trade in animals and animal products.
Based on new scientific information and technological advances, the WOAH constantly updates its standards through an inclusive process of partner international organizations and specialist commissions, ad hoc groups, and working groups. To illustrate, the WOAH has 4 specialist commissions: the aquatic animal health standards commission, the biological standards commission, the scientific commission for animal diseases and the terrestrial animal health standards commission (code commission). The code commission ensures that the terrestrial animal health code reflects current scientific information and contains trade standards. The specialist commissions are responsible for the official recognition of animal health status, provide advice on epidemiology, prevention and control of animal diseases, and deal with scientific and technical issues; accordingly, they are better positioned for coding of animal diseases and data interoperability between WAHIS and ICD -11. 15
Conclusions
Implications for the One Health Approach
There is a compelling need to estimate the magnitude of all human and animal diseases, particularly zoonotic diseases, in a systematic, standardized way (common codes) to compare over time and across geographies, across human and animal populations, to meet the key principles of OHHLEP and translate the One Health approach into actionable policies before 2026. As a case in point at the interface of animal health, human health, food production, and the environment, under a One Health approach, the working group on AMR was established in 2019, replacing the ad hoc group, and is expected to maintain a global perspective and foresight on AMR. This has a 4-pillar work plan: improve awareness and understanding; strengthen knowledge through surveillance and research; support good governance and capacity building at country and regional levels; and encourage the implementation of international standards. A common code on AMR on zoonoses with data interoperability between WAHIS and ICD -11 (as recommended by GLASS) is anticipated from the working group. 16
The ICD-11 has proven to be a global standard with simplified coding to document health data for statistical aggregation. Therefore, in the scope of the One Health approach, we recommend the following:
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a) The categorization of animals and species must be consistent across organizations for good-quality data.
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b) Innovation in methodology to adopt ICD-11 in WAHIS to standardize the estimations of GBADs at the community, subnational, national, regional, and global levels.
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c) Creating codes for all 200 plus zoonotic diseases, either under the existing code (01) of ICD-11 or a new code. This will seamlessly integrate zoonoses data across organizations to achieve the mandates of OHHLEP.
To advance equitable and holistic solutions among the sectors, we need to harmonize and practice One Health through a structured and classified estimate of GBD and GBADs by adopting ICD-11.
Competing interest
The author(s) declare none.
