Economic assessment of an emerging disease: the case of Schmallenberg virus in France.

Schmallenberg virus (SBV) was first detected in 2011 in Germany and then in France in 2012. This study simulates the production of different ruminant systems in France and estimates, through partial budget analyses, the economic cost of SBV at the farm level, under two disease scenarios (a high-impact and low-impact scenario). A partial budget is used to evaluate the financial effect of incremental changes, and includes only resources or production that will be changed. In the high-impact scenario, the estimated impact of SBV ranged from €23 to €43 per cow per year and €19 to €37 per ewe per year. In the low-impact scenario, it was approximately half (for cows) or one-third (for ewes) of this amount. These financial impacts represent 0.6% to 63% of the gross margin, depending on the chosen scenario and the livestock system being considered. The impacts of SBV come mainly from: the extra costs from purchasing and raising replacement heifers and losses in milk production (dairy cows); the losses in calf or lamb production (beef systems and meat sheep); and the losses in milk production and from unsold replacement lambs (dairy sheep). The use of integrated production and economic models enabled the authors to estimate the cost of SBV and to tackle the problem of scarce data, which is a difficulty for most emerging diseases, by their very nature. It also allowed the authors to develop an accurate disease impact assessment for several production systems, over a short time span. Extrapolating from this economic assessment to predict the scenario in coming years depends on the immunity period of the disease and the length of the production cycles.

Le virus de Schmallenberg a été détecté pour la première fois en 2011 en Allemagne, puis en France en 2012. Les auteurs présentent une étude de simulation de plusieurs systèmes de production de ruminants en France, dont l'objectif était d'estimer, à partir d'analyses budgétaires partielles, les coûts économiques du virus de Schmallenberg à l'échelle des exploitations, sous deux scénarios différents (hypothèses d'un fort impact et d'un faible impact de la maladie, respectivement). Une analyse budgétaire partielle sert à évaluer les conséquences financières d'un changement graduel et ne prend en compte que les modifications effectives en termes de ressources et de production. Dans l'hypothèse d'un impact fort de la maladie, l'impact annuel estimé du virus de Schmallenberg variait de 23 à 43 euros par vache et de 19 à 37 euros par brebis. Dans l'hypothèse d'un impact faible, l'impact annuel était deux fois moindre chez les vaches et trois fois moindre chez les brebis que dans la première hypothèse. Ces impacts financiers représentent 0,6 % à 63 % de la marge brute en fonction du scénario choisi et du système de production. Les impacts du virus de Schmallenberg découlent principalement des coûts supplémentaires induits par l'achat et le maintien de génisses de remplacement et d'une baisse de la production de lait (vaches laitières), des pertes de veaux ou d'agneaux (bovins et ovins de boucherie), d'une baisse de la production de lait et du coût des agnelles de remplacement invendues (brebis laitières). L'utilisation de modèles intégrant les aspects économiques et les données de production a permis aux auteurs d'estimer le coût du virus de Schmallenberg malgré la pénurie de données, s'attaquant ainsi à une difficulté inhérente à la plupart des maladies émergentes. Cela leur a également permis d'effectuer une évaluation précise de l'impact sanitaire dans plusieurs systèmes de production, sur une durée courte. La possibilité d'extrapoler à partir de cette évaluation économique un scénario pour les années à venir dépend de la période d'immunité vis-à-vis de la maladie et de la durée des cycles de production.

El virus de Schmallenberg fue detectado por primera vez en 2011 en Alemania y ulteriormente en 2012 en Francia. Los autores describen un estudio en el que se simularon distintos sistemas de producción de rumiantes en Francia y se estimó, con análisis presupuestarios parciales, el coste económico que entrañaría para una explotación el virus de Schmallenberg en dos hipotéticas situaciones sanitarias (una situación con efectos profundos y otra con efectos leves). El análisis presupuestario parcial sirve para evaluar los efectos económicos de cambios graduales, e incluye únicamente aquellos recursos y aspectos de la producción que experimentarán cambios. En la hipótesis de efectos profundos, el impacto estimado de la infección por el virus de Schmallenberg oscilaba entre 23 y 43 euros anuales por vaca y entre 19 y 37 euros anuales por oveja hembra. La hipótesis de efectos leves deparaba importes de aproximadamente la mitad (en el caso de las vacas) o un tercio (en el de las ovejas). Este impacto económico representa del 0,6% al 63% del margen bruto, dependiendo de la hipótesis elegida y del sistema productivo de que se trate. Los efectos de la infección por el virus de Schmallenberg se concretan básicamente en: los costos suplementarios derivados de adquirir y criar vaquillas de sustitución y de obtener una menor producción de leche (vacas lecheras); las pérdidas de terneros o corderos (sistemas de bovino u ovino cárnicos); y los costos derivados de la menor producción de leche y de no vender las corderas de sustitución (ovejas lecheras). El uso de modelos que integran los factores productivos y económicos sirvió a los autores para estimar el costo del virus de Schmallenberg a pesar de la escasez de datos, que, por la propia naturaleza de las enfermedades emergentes, es una dificultad común a la mayoría de ellas. También les permitió evaluar con exactitud el impacto de la enfermedad en distintos sistemas productivos en un breve lapso de tiempo. La realización de extrapolaciones a partir de esta evaluación económica para pronosticar la situación en años venideros depende del periodo de inmunidad respecto de la enfermedad y de la duración de los ciclos productivos.

Herd contact structure based on shared use of water points and grazing points in the Highlands of Ethiopia.

The use of shared common water points (WPs) and grazing points (GPs) at two different levels of administrative aggregation (village and kebelle) in a region of the Highlands of Ethiopia was explored by means of a questionnaire survey and social network analysis. Despite GPs being more abundant than WPs (208 and 154, respectively), individual GPs provide more contact opportunities for animals. There was great variability in the contact structure of the selected villages within kebelles for both networks, with this variability being higher in the GP networks for each kebelle. Contrary to the commonly held view that WPs are critical for the potential transmission of infectious diseases, intervention at GPs in the Ethiopian Highlands may have greater impact on contacts and thereby opportunities for transmission of infectious diseases between flocks. Some villages appear naturally at much lower risk of introducing disease. These findings could help the design of surveillance and control activities for directly transmitted infectious diseases.

Risk factors associated with observed clinical lumpy skin disease in Ethiopia.

A cross-sectional study based on a questionnaire survey was conducted to determine the distribution of lumpy skin disease (LSD) and associated risk factors in three main agro-climatic zones of Ethiopia. A total of 330 questionnaire surveys were collected from 44 peasant associations (PA) distributed in 15 districts. Across agro-climate zones, herd-level LSD prevalence in the midland agro-climate was significantly higher 55.2% [95% confidence interval (CI) 47.5-62.6] than in highland and lowland agro-climate zones. Overall observed LSD prevalence at animal-level was 8.1% (95% CI 7.3-8.9) and observed mortality was 2.12% (95% CI 1.73-2.6). The odds ratio (OR) of LSD occurrence in midland vs. highland and lowland vs. highland zones was 3.86 (95% CI 2.61-5.11) and 4.85 (95% CI 2.59-7.1), respectively. Significantly high risk of LSD occurrence was associated with communal grazing and watering management (OR 4.1, 95% CI 2.02-6.18) and introduction of new cattle (OR 8.5, 95% CI 6.0-11.0). Our findings describe the distribution of LSD in different agro-climates in Ethiopia along with associated risk factors, and can help shed light on the epidemiology of LSD in other African countries suffering from the disease.

Lumpy skin disease in Ethiopia: seroprevalence study across different agro-climate zones.

A cross-sectional study was conducted to estimate the seroprevalence of lumpy skin disease (LSD) in the different agro-climatic zones prevailing in Ethiopia. A total of 2368 serum samples were collected from 42 kebeles located in 15 districts and tested using indirect fluorescent antibody test (IFAT) and virus neutralization test (VNT). The herd and animal true LSD serological prevalence were estimated in each agro-climate zone using a Bayesian model. The intra-cluster correlation coefficient (ICC) was evaluated using a random-effect model. According to the serological prevalence estimations, LSD affected differently the three agro-climatic zones considered. Herd level seroprevalence was higher in the midland agro-climate zone 64% (95% CI: 53-74) as compared to the highland 26% (95% CI: 17-36) and the lowland 50% (95% CI: 40-60) agro-climates. Animal level seroprevalence in infected herds was also higher in the midland agro-climate zone 31% (95% CI: 24-40) than in the highland and lowland zones (24% (95% CI: 18-31) and 23% (95% CI: 18-29), respectively). Higher ICC value in the highland agro-climate zone implies that increased sample sizes should be particularly required for this zone in future studies to estimate LSD prevalence or incidence with a desired precision level. This seroprevalence study also suggests that the prevalence of LSD infection in Ethiopia is higher than what has been previously reported. In the light of these updated estimations, we discuss options to trigger appropriate control measures in the future.

Epidemiological aspects and financial impact of lumpy skin disease in Ethiopia.

The financial cost of clinical Lumpy Skin Disease (LSD) and the financial benefit of its control through vaccination were studied based on questionnaire survey in Oromia region of Ethiopia from the perspective of livestock farmers. Production loss impacts for local zebu cattle were compared with those of Holstein Friesian (HF)/crossbred cattle in the study area. Annual cumulative incidence of LSD infection in HF/crossbred and local zebu cattle were 33.93% (95% CI: 30.92-36.94) and 13.41% (95% CI: 12.6-14.25) respectively and significantly different (p<0.05). Annual mortality was also significantly higher in HF/crossbred 7.43% (95% CI: 5.76-9.10) than in local zebu cattle 1.25% (95% CI: 0.98-1.52). The annual financial cost was calculated as the sum of the average production losses due to morbidity and mortality arising from milk loss, beef loss, traction power loss, and treatment and vaccination costs at the herd level. The financial cost in infected herds was estimated to be USD 6.43 (5.12-8) per head for local zebu and USD 58 (42-73) per head for HF/crossbred cattle. A partial budget analysis was used to estimate the financial benefit of an annual vaccination program in both the local zebu and HF/crossbred cattle farming systems. The marginal rate of return (MRR) gained from this control intervention was estimated to be 34 (3400%) and the net benefit per head was USD 1 for local zebu and USD 19 for HF/crossbred cattle. Vaccination thus enabled financial costs due to LSD to be reduced by 17% per head in local zebu herds and 31% per head in HF/crossbred herds. These results could provide guidance to producers and the government in their endeavors to control the disease.