How can we realise the full potential of animal health systems for delivering development and health outcomes?

Animal health services play an essential role in supporting livestock production, with the potential to address the challenges of hunger, poverty, health, social justice and environmental health as part of the path towards the Sustainable Development Goal (SDG) defined in the United Nations, 2030 Agenda. However, the provision of animal health services remains chronically underfunded. Although the aspiration that â€Ëœno one will be left behind' is core to the SDG agenda, animal health service provision still fails to meet the basic needs of many of the poorest livestock owners. This review draws largely on experience from Tanzania and highlights the obstacles to equitable provision of animal health services, as well as identifying opportunities for improvement. Delivery models that rely on owners paying for services, whether through the private sector or public?private partnerships, can be effective for diseases that are of clear economic importance to animal keepers, particularly in more market-orientated production systems, but are currently constrained by issues of access, affordability, availability and quality. Substantial challenges remain when attempting to control diseases that exert a major burden on animal or human health but are less well recognised, as well as in the delivery of veterinary public health or other public good interventions. Here, the authors propose solutions that focus on: improving awareness of the potential for animal health services to address the SDGs, particularly those concerning public and environmental health; linking this more explicitly with advocacy for increased investment; ensuring that the voices of stakeholders are heard, particularly those of the rural poor; and embracing a cross-cutting and expanded vision for animal health services to support more adaptive development of livestock systems.

Les services de santé animale accomplissent une fonction essentielle en faveur de la production animale tout en ayant un potentiel d'action pour relever les défis de la faim, de la pauvreté, de la santé, de la justice sociale et de la santé dans la perspective des objectifs de développement durable (ODD) définis dans l'Agenda 2030 des Nations Unies. Toutefois, la prestation de services de santé animale souffre d'un sous-financement chronique. Bien que l'aspiration de « ne laisser personne pour compte ¼ soit au coeur du programme des ODD, à ce jour la prestation de services de santé animale ne parvient pas encore à répondre aux besoins fondamentaux de nombreux propriétaires de bétail parmi les plus pauvres. Les auteurs s'appuient largement sur l'expérience de la Tanzanie pour mettre en évidence les obstacles à une prestation équitable de services de santé animale, et relever des perspectives d'amélioration. Les modèles de prestation assurés dans le cadre du secteur privé ou de partenariats public-privé et reposant sur le paiement des services par les propriétaires se révèlent efficaces lorsqu'il s'agit de maladies qui ont une importance économique évidente pour les détenteurs d'animaux, en particulier dans les systèmes de production orientés vers le marché, mais ils sont actuellement limités par des problèmes d'accès, de coût, de disponibilité de l'offre et de qualité. Des difficultés encore plus grandes subsistent lorsqu'il s'agit de lutter contre des maladies moins connues bien qu'ayant un impact important sur la santé animale ou humaine, ou d'assurer des services de santé publique vétérinaire ou d'autres interventions relevant du bien public. Les auteurs proposent des solutions centrées sur : une meilleure sensibilisation concernant le potentiel des services de santé animale à réaliser les ODD, en particulier ceux qui portent sur la santé publique et la santé environnementale ; la mise en place de liens plus explicites avec les plaidoyers en faveur d'investissements accrus ; des mesures garantissant que les voix de toutes les parties prenantes soient entendues, en particulier celles des pauvres du monde rural ; l'adoption d'une stratégie transversale et de grande ampleur pour les services de santé animale en faveur d'un développement plus adaptatif des systèmes d'élevage.

Los servicios de sanidad animal cumplen una esencial función de apoyo a la producción ganadera, potencialmente útil para abordar problemas relacionados con el hambre, la pobreza, la salud, la justicia social y la salud ambiental como parte del camino hacia los Objetivos de Desarrollo Sostenible (ODS) marcados en la Agenda 2030 de las Naciones Unidas. Sin embargo, la prestación de servicios zoosanitarios está lastrada por un déficit crónico de financiación. Aunque en la base misma de los ODS late la aspiración de «no dejar a nadie atrás¼, la prestación estos servicios aún no alcanza para responder a las necesidades básicas de muchos de los propietarios de ganado más pobres. Los autores, basándose principalmente en la experiencia de Tanzania, destacan los obstáculos que dificultan una prestación equitativa de servicios zoosanitarios y señalan las posibilidades existentes para progresar al respecto. Los modelos de prestación que requieren que el propietario pague por los servicios recibidos, ya sea del sector privado o de alianzas publicoprivadas, pueden resultar eficaces en el caso de enfermedades que revisten una clara importancia económica para los productores, especialmente en sistemas productivos con una marcada orientación comercial, aunque actualmente se ven lastrados por problemas de acceso, asequibilidad, disponibilidad y calidad. Por otro lado, subsisten dificultades de gran calado a la hora de combatir enfermedades menos reconocidas, aunque estas entrañen una pesada carga sanitaria o zoosanitaria, y también a la hora de implantar medidas de salud pública veterinaria u otras intervenciones de interés público. Los autores proponen soluciones centradas en: dar mejor a conocer el potencial que encierran los servicios de sanidad animal para perseguir los ODS, sobre todo los relacionados con la salud pública y ambiental; vincular más explícitamente esto último a la labor de sensibilización para lograr inversiones más cuantiosas; hacer oír la voz de todos los interesados, en especial la de los pobres de zonas rurales; y adoptar una visión más amplia y transversal de los servicios zoosanitarios para favorecer un desarrollo más flexible de los sistemas ganaderos.

Identifying Age Cohorts Responsible for Peste Des Petits Ruminants Virus Transmission among Sheep, Goats, and Cattle in Northern Tanzania.

Peste des petits ruminants virus (PPRV) causes a contagious disease of high morbidity and mortality in global sheep and goat populations. To better control this disease and inform eradication strategies, an improved understanding of how PPRV transmission risk varies by age is needed. Our study used a piece-wise catalytic model to estimate the age-specific force of infection (FOI, per capita infection rate of susceptible hosts) among sheep, goats, and cattle from a cross-sectional serosurvey dataset collected in 2016 in Tanzania. Apparent seroprevalence increased with age, reaching 53.6%, 46.8%, and 11.6% (true seroprevalence: 52.7%, 52.8%, 39.2%) for sheep, goats, and cattle, respectively. Seroprevalence was significantly higher among pastoral animals than agropastoral animals across all ages, with pastoral sheep and goat seroprevalence approaching 70% and 80%, respectively, suggesting pastoral endemicity. The best fitting piece-wise catalytic models merged age groups: two for sheep, three for goats, and four for cattle. The signal of these age heterogeneities were weak, except for a significant FOI peak among 2.5-3.5-year-old pastoral cattle. The subtle age-specific heterogeneities identified in this study suggest that targeting control efforts by age may not be as effective as targeting by other risk factors, such as production system type. Further research should investigate how specific husbandry practices affect PPRV transmission.

Pastoral production is associated with increased peste des petits ruminants seroprevalence in northern Tanzania across sheep, goats and cattle.

Peste des petits ruminants virus (PPRV) causes a contagious disease of high morbidity and mortality in small ruminant populations globally. Using cross-sectional serosurvey data collected in 2016, our study investigated PPRV seroprevalence and risk factors among sheep, goats and cattle in 20 agropastoral (AP) and pastoral (P) villages in northern Tanzania. Overall observed seroprevalence was 21.1% (95% exact confidence interval (CI) 20.1-22.0) with 5.8% seroprevalence among agropastoral (95% CI 5.0-6.7) and 30.7% among pastoral villages (95% CI 29.3-32.0). Seropositivity varied significantly by management (production) system. Our study applied the catalytic framework to estimate the force of infection. The associated reproductive numbers (R0) were estimated at 1.36 (95% CI 1.32-1.39), 1.40 (95% CI 1.37-1.44) and 1.13 (95% CI 1.11-1.14) for sheep, goats and cattle, respectively. For sheep and goats, these R0 values are likely underestimates due to infection-associated mortality. Spatial heterogeneity in risk among pairs of species across 20 villages was significantly positively correlated (R2: 0.59-0.69), suggesting either cross-species transmission or common, external risk factors affecting all species. The non-negligible seroconversion in cattle may represent spillover or cattle-to-cattle transmission and must be investigated further to understand the role of cattle in PPRV transmission ahead of upcoming eradication efforts.

Analysing livestock network data for infectious disease control: an argument for routine data collection in emerging economies.

Livestock movements are an important mechanism of infectious disease transmission. Where these are well recorded, network analysis tools have been used to successfully identify system properties, highlight vulnerabilities to transmission, and inform targeted surveillance and control. Here we highlight the main uses of network properties in understanding livestock disease epidemiology and discuss statistical approaches to infer network characteristics from biased or fragmented datasets. We use a 'hurdle model' approach that predicts (i) the probability of movement and (ii) the number of livestock moved to generate synthetic 'complete' networks of movements between administrative wards, exploiting routinely collected government movement permit data from northern Tanzania. We demonstrate that this model captures a significant amount of the observed variation. Combining the cattle movement network with a spatial between-ward contact layer, we create a multiplex, over which we simulated the spread of 'fast' ( R0 = 3) and 'slow' ( R0 = 1.5) pathogens, and assess the effects of random versus targeted disease control interventions (vaccination and movement ban). The targeted interventions substantially outperform those randomly implemented for both fast and slow pathogens. Our findings provide motivation to encourage routine collection and centralization of movement data to construct representative networks. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'. This theme issue is linked with the earlier issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'.

Household socio-economic position and individual infectious disease risk in rural Kenya.

The importance of household socio-economic position (SEP) in shaping individual infectious disease risk is increasingly recognised, particularly in low income settings. However, few studies have measured the extent to which this association is consistent for the range of pathogens that are typically endemic among the rural poor in the tropics. This cross-sectional study assessed the relationship between SEP and human infection within a single community in western Kenya using a set of pathogens with diverse transmission routes. The relationships between household SEP and individual infection with Plasmodium falciparum, hookworm (Ancylostoma duodenale and/or Necator americanus), Entamoeba histolytica/dispar, Mycobacterium tuberculosis, and HIV, and co-infections between hookworm, P. falciparum and E. histolytica/dispar, were assessed using multivariable logistic and multinomial regression. Individuals in households with the lowest SEP were at greatest risk of infection with P. falciparum, hookworm and E. histolytica/dispar, as well as co-infection with each pathogen. Infection with M. tuberculosis, by contrast, was most likely in individuals living in households with the highest SEP. There was no evidence of a relationship between individual HIV infection and household SEP. We demonstrate the existence of a household socio-economic gradient within a rural farming community in Kenya which impacts upon individual infectious disease risk. Structural adjustments that seek to reduce poverty, and therefore the socio-economic inequalities that exist in this community, would be expected to substantially reduce overall infectious disease burden. However, policy makers and researchers should be aware that heterogeneous relationships can exist between household SEP and infection risk for different pathogens in low income settings.

The topology of between-herd cattle contacts in a mixed farming production system in western Kenya.

In many livestock production systems in sub-Saharan Africa, cattle are owned by individual keepers but regularly mix with animals from other herds while grazing communal land, at watering points or through the use of shared bulls for breeding and ploughing. Such contacts may have important implications for disease transmission and control but are not well documented. We describe between-farm contacts in Kimilili sub-county of Bungoma County, a mixed farming area of predominately smallholder farmers. Between-farm contacts occurring during grazing or at shared water points over the past four weeks were captured in seven randomly selected villages using a photo-elicitation tool. The use of shared bulls for breeding and ploughing and cattle introductions from farms within the same village in the past 12 months were also captured. Contact networks were constructed for each contact type in each village. In total 329 farms were included in the study. Networks resembled undirected scale-free graphs with a network density ranging between 9.6 and 14.0. Between 45.6 and 100% of the farms in each study village had been in contact over the past four weeks through grazing and watering contacts. Between 88.9 and 100% were considered to have been in contact over the past 12 months. The topology of the networks was heterogeneous, with some farms exhibiting a high degree of contact. The degree of farm contact and distances between farms were negatively correlated (Pearson correlation coefficient range -0.2 to -0.4). Effective disease control and surveillance must take into consideration the frequency and range of contacts that occur between farms within a single village. Cattle keepers are highly interconnected and pathogens that are transmitted through direct or indirect animal contact would be expected to spread rapidly in the study system. However, the observed heterogeneity in between-farm contact may present opportunities for interventions to be targeted to particular herds to limit infectious disease spread.

One Health contributions towards more effective and equitable approaches to health in low- and middle-income countries.

Emerging zoonoses with pandemic potential are a stated priority for the global health security agenda, but endemic zoonoses also have a major societal impact in low-resource settings. Although many endemic zoonoses can be treated, timely diagnosis and appropriate clinical management of human cases is often challenging. Preventive 'One Health' interventions, e.g. interventions in animal populations that generate human health benefits, may provide a useful approach to overcoming some of these challenges. Effective strategies, such as animal vaccination, already exist for the prevention, control and elimination of many endemic zoonoses, including rabies, and several livestock zoonoses (e.g. brucellosis, leptospirosis, Q fever) that are important causes of human febrile illness and livestock productivity losses in low- and middle-income countries. We make the case that, for these diseases, One Health interventions have the potential to be more effective and generate more equitable benefits for human health and livelihoods, particularly in rural areas, than approaches that rely exclusively on treatment of human cases. We hypothesize that applying One Health interventions to tackle these health challenges will help to build trust, community engagement and cross-sectoral collaboration, which will in turn strengthen the capacity of fragile health systems to respond to the threat of emerging zoonoses and other future health challenges. One Health interventions thus have the potential to align the ongoing needs of disadvantaged communities with the concerns of the broader global community, providing a pragmatic and equitable approach to meeting the global goals for sustainable development and supporting the global health security agenda.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'.

Environmental predictors of bovine Eimeria infection in western Kenya.

Eimeriosis is caused by a protozoan infection affecting most domestic animal species. Outbreaks in cattle are associated with various environmental factors in temperate climates but limited work has been done in tropical settings. The objective of this work was to determine the prevalence and environmental factors associated with bovine Eimeria spp. infection in a mixed farming area of western Kenya. A total of 983 cattle were sampled from 226 cattle-keeping households. Faecal samples were collected directly from the rectum via digital extraction and analysed for the presence of Eimeria spp. infection using the MacMaster technique. Individual and household level predictors of infection were explored using mixed effects logistic regression. The prevalence of individual animal Eimeria infection was 32.8% (95% CI 29.9-35.9). A positive linear relationship was found between risk of Eimeria infection and increasing temperature (OR = 1.4, 95% CI 1.06-1.86) and distance to areas at risk of flooding (OR = 1.49, 95% CI 1.17-1.91). There was weak evidence of non-linear relationship between Eimeria infection and the proportion of the area around a household that was classified as swamp (OR = 1.12, 95% CI 0.87-1.44; OR (quadratic term) = 0.85, 95% CI 0.73-1.00), and the sand content of the soil (OR = 1.18, 95% CI 0.91-1.53; OR (quadratic term) = 1.1, 95% CI 0.99-1.23). The risk of animal Eimeria spp. infection is influenced by a number of climatic and soil-associated conditions.

Assessing the impact of tailored biosecurity advice on farmer behaviour and pathogen presence in beef herds in England and Wales.

The term 'biosecurity' encompasses many measures farmers can take to reduce the risk of pathogen incursion or spread. As the best strategy will vary between settings, veterinarians play an important role in assessing risk and providing advice, but effectiveness requires farmer acceptance and implementation. The aim of this study was to assess the effectiveness of specifically-tailored biosecurity advice packages in reducing endemic pathogen presence on UK beef suckler farms. One hundred and sixteen farms recruited by 10 veterinary practices were followed for three years. Farms were randomly allocated to intervention (receiving specifically-tailored advice, with veterinarians and farmers collaborating to develop an improved biosecurity strategy) or control (receiving general advice) groups. A spreadsheet-based tool was used annually to attribute a score to each farm reflecting risk of entry or spread of bovine viral diarrhoea virus (BVDV), bovine herpesvirus-1 (BHV1), Mycobacterium avium subsp. paratuberculosis (MAP), Leptospira interrogans serovar hardjo (L. hardjo) and Mycobacterium bovis (M. bovis). Objectives of these analyses were to identify evidence of reduction in risk behaviours during the study, as well as evidence of reductions in pathogen presence, as indications of effectiveness. Risk behaviours and pathogen prevalences were examined across study years, and on intervention compared with control farms, using descriptive statistics and multilevel regression. There were significant reductions in risk scores for all five pathogens, regardless of intervention status, in every study year compared with the outset. Animals on intervention farms were significantly less likely than those on control farms to be seropositive for BVDV in years 2 and 3 and for L. hardjo in year 3 of the study. Variations by study year in animal-level odds of seropositivity to BHV1 or MAP were not associated with farm intervention status. All farms had significantly reduced odds of BHV1 seropositivity in year 2 than at the outset. Variations in farm-level MAP seropositivity were not associated with intervention status. There were increased odds of M. bovis on intervention farms compared with control farms at the end of the study. Results suggest a structured annual risk assessment process, conducted as a collaboration between veterinarian and farmer, is valuable in encouraging improved biosecurity practices. There were some indications, but not conclusive evidence, that tailored biosecurity advice packages have potential to reduce pathogen presence. These findings will inform development of a collaborative approach to biosecurity between veterinarians and farmers, including adoption of cost-effective strategies effective across pathogens.

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya.

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization.