Peste des petits ruminants (PPR) is an acute and highly contagious viral disease that predominantly affects small ruminants (sheep and goats). PPR has a widespread distribution spanning West, Central and East Africa, the Arabic peninsula, the Middle East and southern Asia. The potential and real economic impacts of PPR outbreaks are high and often disproportionately affect the poorer sections of the society. This is especially evident in developing countries where sheep and goats play an integral role in subsistence farming to supply food or goods for trade. Since rinderpest has been eradicated, PPR has become one of the principal infectious diseases of livestock in Africa. FAO and the World Organisation for Animal Health (OIE) are currently activating the international community targeting the eradication of PPR by 2030. PPR poses a risk to about 50 million sheep and goats in the entire Southern Africa region particularly because Tanzania and DRC have declared outbreaks in the recent years. The official services of the region need to develop strategies on how to limit the spread of the disease in the event of introduction in PPR free countries. Indeed, most of the countries are not well prepared for the diagnostic, disease containment, and legislation issues. Based on collection of available data and estimation of parameters regarding the small ruminants demography, the type of husbandry, the legal and illegal movements and trade, and role of other potential hosts including wildlife, modelling approaches -i.e. Quantitative risk assessment (QRA) and multicriteria decision analysis (MCDA) - are undertaken at the regional level in order to quantify the risk of introduction and to map the suitable areas for PPR spreading and maintenance. The pathways of introduction are described and several at - risk areas are characterized. A zoning process is proposed at the regional level. The outputs of the models could support the prevention of disease incursion in PPR free areas and the definition of management options: risk - based surveillance and control strategies, capacity building of stakeholders and adaptation of sanitary policy.
International audience ; The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i) reservoir hosts, (ii) vectors, both characterized by their diversity, abundance and competence, (iii) and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV) circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85). Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79-0.92), and a specificity of 68% (95% CI: 0.66-0.71). Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.
International audience ; The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i) reservoir hosts, (ii) vectors, both characterized by their diversity, abundance and competence, (iii) and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV) circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85). Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79-0.92), and a specificity of 68% (95% CI: 0.66-0.71). Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.
International audience ; The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i) reservoir hosts, (ii) vectors, both characterized by their diversity, abundance and competence, (iii) and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV) circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85). Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79-0.92), and a specificity of 68% (95% CI: 0.66-0.71). Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.
International audience ; The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i) reservoir hosts, (ii) vectors, both characterized by their diversity, abundance and competence, (iii) and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV) circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85). Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79-0.92), and a specificity of 68% (95% CI: 0.66-0.71). Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.
The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i) reservoir hosts, (ii) vectors, both characterized by their diversity, abundance and competence, (iii) and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV) circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85). Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79–0.92), and a specificity of 68% (95% CI: 0.66–0.71). Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.
In 2006, the detection of the avian influenza (flu) H5N1 virus in Africa caused great concern: the virus could spread to the whole continent, and then be reintroduced to Europe by migratory birds. Epidemiological surveillance programmes were set up and national mechanisms strengthened with the support of international organisations. At the same time, research programmes were launched to describe and under-stand the virus transmission processes in Africa, and to assess the risks. Among these programmes, the GRIPAVI project is aimed at characterizing the circulation of avian influenza viruses and Newcastle disease in both wild birds and domestic poultry. It shows that the African continent is not free from risk and that vigilance should continue. By specifying the virus persistence mechanisms in Africa and identifying risk situations, it proposes avenues for targeting surveillance and control strategies and thereby making them more efficient.
En 2006, la détection du virus de l'influenza (grippe) aviaire H5N1 en Afrique suscite une grande inquiétude : le virus pourrait se propager à l'ensemble du continent, puis être réintroduit en Europe par les oiseaux migrateurs. Des programmes de surveillance épidémiologique et de renforcement des dispositifs nationaux sont mis en place, appuyés par des organismes internationaux. En parallèle, des programmes de recherche sont lancés pour décrire et comprendre les processus de transmission de ce virus en Afrique, et évaluer les risques. Parmi eux, le projet Gripavi vise à caractériser la circulation des virus d'influenza aviaire et de la maladie de Newcastle à la fois dans l'avifaune sauvage et la volaille domestique. Il montre que le continent africain n'est pas exempt de risques et que la vigilance doit rester de mise. En précisant les modes de persistance du virus en Afrique et en identifiant des situations à risque, il met au jour des pistes pour cibler les stratégies de surveillance et de contrôle, et en améliorer ainsi l'efficacité.
Live animal trade is considered a major mode of introduction of viruses from enzootic foci into disease-free areas. Due to societal and behavioural changes, some wild animal species may nowadays be considered as pet species. The species diversity of animals involved in international trade is thus increasing. This could benefit pathogens that have a broad host range such as arboviruses. The objective of this study was to analyze the risk posed by live animal imports for the introduction, in the European Union (EU), of four arboviruses that affect human and horses: Eastern and Western equine encephalomyelitis, Venezuelan equine encephalitis and Japanese encephalitis. Importation data for a five-years period (2005-2009, extracted from the EU TRACES database), environmental data (used as a proxy for the presence of vectors) and horses and human population density data (impacting the occurrence of clinical cases) were combined to derive spatially explicit risk indicators for virus introduction and for the potential consequences of such introductions. Results showed the existence of hotspots where the introduction risk was the highest in Belgium, in the Netherlands and in the north of Italy. This risk was higher for Eastern equine encephalomyelitis (EEE) than for the three other diseases. It was mainly attributed to exotic pet species such as rodents, reptiles or cage birds, imported in small-sized containments from a wide variety of geographic origins. The increasing species and origin diversity of these animals may have in the future a strong impact on the risk of introduction of arboviruses in the EU.
Dwarfing the direct losses due to ruminant abortions and flock mortality, the main economic impact of RVF is systemic and ensues from the trade restrictions aimed at its containment. Indeed, past outbreaks of RVF in East Africa and Middle East came as disturbing events in a commercial context of high specialization in trade of small ruminants and interdependence between East-African exporters and the Middle-Eastern importing countries. The two successive bans imposed by Middle-Eastern countries on livestock products coming from the Horn of Africa in 1998-1999 and 2000-2002 highlighted this interdependence. Both bans caused an abrupt stop in exportations from IGAD countries. Nevertheless, the impact of the outbreaks motivating these bans differed due to their unique timing with regard to the Muslim celebrations that trigger the main flow of livestock from the Horn of Africa to Mecca. Hence, in 2000, the worst impact was observed on pastoralist households because the ban was imposed in September, prior to the Haj festival, when the main seasonal export flow had not been realized yet. Regarding the 1997 outbreak, the ban was implemented only in February 1998, after the main trade flow had occurred. The impacts of the bans on Somalia were particularly severe, due to the high specialization of the concerned region in an export-oriented livestock sector, benefitting from a niche market organized around the above-mentioned religious festivals and Arab consumers preferences. The country was all the more affected, as they own two main ports involved in this trade, i.e. Berbera (Somaliland) and Bossaso (Puntland). Prior to the bans, the size of the export market from Somalia to Saudi Arabia and the United Arab Emirates was estimated around US$600 million, with Saudi Arabia representing 66% of the total. The bans led the Somali livestock market to collapse. Losses for the livestock industry were estimated at US$109 million and US$326 million, for the first and second ban respectively. The government also directly incurred an important loss around US$45 million from foregone export taxes and docking fees. In the same time, livestock exporters lost a net cumulative profit of US$330 million, whereas producers estimated their annual losses at over US$8 million. Hence, the successive RVF-related trade bans impacted the employment rate, the public treasury, the exchange rate of national currency and thus, the price of imported goods, inducing a general inflationary pressure and important socio-economic upheavals. More generally, the livestock market in the whole East Africa was affected, due to the fall in prices caused by the loss of outlets for livestock. Using market equilibrium models taking these shocks into account, the impact of the trade bans on the Somali region of Ethiopia were estimated at a 36% fall of the GDP. Other impacts originated in the closure of markets inside East Africa, being part of national control strategies. In Kenya, e.g., the closure of the Garissa Market, which is a major outlet for Somali and Ethiopian livestock, resulted in a more than 25% decrease in the price of cattle, inducing a total loss of US$10 million for the value chain. The emergency destocking response of distressed households also participated to the fall in prices and worsening of terms of trade. Together with flock mortality and abortion, destocking moreover affects the herds' dynamics on the long run and the commercial potential of households. These mechanisms show greater impact on smallholders, due to threshold effects in livestock capitalisation and the loss in risk management ability in such variable environmental conditions. In the Middle East too, the bans showed drastic economic impacts. In Yemen, e.g., the bans caused a loss of US$15 million from foregone custom taxes and US$27 million profit losses for traders. The two bans, combined with the prolonged ban maintained till 2009 by Saudi Arabia on Somalia, contributed to a restructuration of trade within and between the two regions. Indeed, trade actors soon reorganized their activity, as highlighted through official figures, notwithstanding the importance of informal trade. Hence, Yemen and the United Arab Emirates appeared as major alternative entry points on Arab Peninsula for Somali livestock. The latter could also transit through Djibouti or Sudan to reach Saudi Arabia. Benefitting from the prolonged bans on Somalia, the port of Djibouti emerged as a major player in the region between 2006 and 2009, thanks to massive investment in port infrastructures and agreements with Saudi importers. Therefore the private sector played a considerable role in adapting to new risks. The Djibouti port diverted much of the livestock trade previously handled at the Berbera and Bossaso ports. On this occasion, as it has been the case in Somalia after ban lifting in 2009, the Middle East has been a source of investment for the Horn of Africa for biosecurity infrastructure. Finally, the second ban led to the emergence of Australia as a major livestock supplier for Saudi Arabia from 2000 till now, and to a certain a point Australia has been a country of major Saudi investments which is seen as another way of adapting for some major value chain agents. In the two last decades, the intraregional livestock trade grew rapidly in East Africa, spurred by the urban demand. Most of this trade is informal, thus lacking official figures. It nevertheless shows a great importance regarding poverty alleviation aspects, the small to medium actors being the main operators of this trade. In recent years, a considerable growth in recorded intraregional trade is noticed, mainly due to a growth of recorded exports from Ethiopia to neighboring countries, as a result of a policy aiming at the facilitation of registration procedures through the CAC/AP-system. As a conclusion, livestock export to Middle East and the growing intraregional East-African livestock trade are both threatened by RVF-linked bans due to loss of outlets and price volatility. Thus, stability of the livestock sector being crucial to human and economic development in the region, a high priority must be given to RVF prevention and control, as supported by figures of impact of past outbreaks. ; Peer reviewed
Live animal trade is considered a major mode of introduction of viruses from enzootic foci into disease-free areas. Due to societal and behavioural changes, some wild animal species may nowadays be considered as pet species. The species diversity of animals involved in international trade is thus increasing. This could benefit pathogens that have a broad host range such as arboviruses. The objective of this study was to analyze the risk posed by live animal imports for the introduction, in the European Union (EU), of four arboviruses that affect human and horses: Eastern and Western equine encephalomyelitis, Venezuelan equine encephalitis and Japanese encephalitis. Importation data for a five-years period (2005-2009, extracted from the EU TRACES database), environmental data (used as a proxy for the presence of vectors) and horses and human population density data (impacting the occurrence of clinical cases) were combined to derive spatially explicit risk indicators for virus introduction and for the potential consequences of such introductions. Results showed the existence of hotspots where the introduction risk was the highest in Belgium, in the Netherlands and in the north of Italy. This risk was higher for Eastern equine encephalomyelitis (EEE) than for the three other diseases. It was mainly attributed to exotic pet species such as rodents, reptiles or cage birds, imported in small-sized containments from a wide variety of geographic origins. The increasing species and origin diversity of these animals may have in the future a strong impact on the risk of introduction of arboviruses in the EU.
The past two decades have seen an accumulation of theoretical and empirical evidence for the interlinkages between human health and well-being, biodiversity and ecosystem services, and agriculture. The COVID-19 pandemic has highlighted the devastating impacts that an emerging pathogen, of animal origin, can have on human societies and economies. A number of scholars have called for the wider adoption of "One Health integrated approaches" to better prevent, and respond to, the threats of emerging zoonotic diseases. However, there are theoretical and practical challenges that have precluded the full development and practical implementation of this approach. Whilst integrated approaches to health are increasingly adopting a social-ecological system framework (SES), the lack of clarity in framing the key concept of resilience in health contexts remains a major barrier to its implementation by scientists and practitioners. We propose an operational framework, based on a transdisciplinary definition of Socio-Ecological System Health (SESH) that explicitly links health and ecosystem management with the resilience of SES, and the adaptive capacity of the actors and agents within SES, to prevent and cope with emerging health and environmental risks. We focus on agricultural transitions that play a critical role in disease emergence and biodiversity conservation, to illustrate the proposed participatory framework to frame and co-design SESH interventions. Finally, we highlight critical changes that are needed from researchers, policy makers and donors, in order to engage communities and other stakeholders involved in the management of their own health and that of the underpinning ecosystems.
