Impact Of Schmallenberg Virus Research Articles

Survey to understand impact of Schmallenberg virus

Survey to understand impact of Schmallenberg virus

Low incidence of Schmallenberg virus infection in natural cases of abortion in domestic ruminants in Hungary.

An epizootic caused by a new orthobunyavirus called Schmallenberg virus (SBV) was recognised in European ruminants in 2011 and 2012. The re-emergence of the infection was reported in several countries in the subsequent years. Although the main clinical sign of SBV infection is abortion, the impact of SBV in natural cases of abortion in domestic ruminants had not been systematically examined before this study. The aim of the study was to investigate the role of SBV infection and to compare it to the importance of other causes of abortion by examining 537 natural cases of abortion that had occurred between 2011 and 2017 in Hungary. The cause of abortion was determined in 165 (31%) cases. An infectious cause was proved in 88 (16%) cases. SBV infection was found only in a total of four cases (0.8%) using real-time polymerase chain reaction. Three of them proved to be inapparent SBV infection, and one case was attributed to SBV-induced abortion by detecting non-purulent encephalitis and SBV nucleoprotein by immunohistochemistry in a brain tissue sample. According to the results, SBV played a minor role in natural cases of domestic ruminant abortion in Hungary during the 7-year period following the first SBV outbreak in 2011.

Highs and Lows of Lambing Time: Sheep Farmers' Perceptions of the First Outbreak of Schmallenberg Disease in South West England on Their Well-Being.

The outbreak of a previously unknown and new disease in the United Kingdom, known as ‘Schmallenberg disease’, a disease associated with abortions, stillbirths and fetal deformities in naïve ewes, was reported for the first time in South West England during the 2012/13 early lambing season. Epidemiological studies confirmed that the Schmallenberg virus (SBV) had a severe negative impact upon animal welfare and the productivity of affected flocks. By contrast, there was a specific lack of research on the impact of SBV on sheep farmer well-being. This study aimed to improve our understanding of sheep farmers’ experiences of Schmallenberg disease, and the impact of the first outbreak on sheep farmer well-being during the 2012/13 early lambing season in South West England. Face-to-face, semi-structured interviews with six farmers with small flocks of pedigree and purebred sheep in South West England were conducted in 2013. The data were analysed via thematic analysis. The main themes regarding the impact of disease on farmer well-being included: (i) emotional highs and lows are part of a normal lambing season; (ii) negative emotions and memories associated with the Schmallenberg disease outbreak; and (iii) resilience and coping with the unexpected disease outbreak. These novel data present preliminary findings from a small number of sheep farmers, and indicate that for some farmers, an unexpected outbreak of a new and emerging disease for the first time during lambing, and dealing with high levels of dystocia, deformities and deaths in their animals, had a negative impact on their emotional well-being during the peak period of the sheep production cycle.

Association of clinical signs after acute Schmallenberg virus infection with milk production and fertility in Swiss dairy cows

Since its first occurrence in August 2011 in Germany and the Netherlands, the Schmallenberg virus (SBV) spread rapidly across Europe, where it caused production losses and abortions in ruminants as well as congenital malformations in the offspring of affected animals. Several studies have investigated the impact of SBV on fertility and production parameters in dairy cows at herd level. However, the impact of clinical disease at the animal level remained undetermined.This study aimed at estimating the impact of clinical disease during and after an infection with SBV on production and fertility parameters in individual Swiss dairy cows. Sixty-seven case and twenty-four control herds were selected according to whether cows had been showing clinical signs indicative of SBV during the epidemic from July to December 2012 in Switzerland. Of these 91 farms, production and fertility data from 388 cows with clinical signs from case herds were collected over a time period of four years, and compared to data from 932 cows without clinical signs originating from case or control herds. Milk yield, somatic cell count, number of inseminations and non-return at day 56 were analysed by means of hierarchical multivariable regression analysis.A significant drop in milk yield was observed in all groups during the SBV epidemic compared to the time before the infection, which amounted to 1.9kg per test day for clinical animals, 1.1kg for non-clinical animals from case herds and 0.6kg for non-clinical animals from control herds. A prolonged effect on milk yield was observed in clinical cows for about one year, suggesting that animals with clinical disease might not return to their previous milk production level in the current lactation after an acute infection with SBV. Clinical animals showed a significantly higher somatic cell count during the epidemic compared to the time before the infection. The number of inseminations per cow and production cycle was higher for clinical animals during the epidemic compared to the time periods before and after, but not significantly higher than for non-clinical animals from case and control herds. No difference regarding non-return at day 56 was found. Although the overall impact of the SBV epidemic in Switzerland was limited, the consequences could be substantial in farms with a high prevalence of clinical disease.

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.

The impact of infection with Schmallenberg virus on weaning rate in Irish sheep flocks

Schmallenberg virus (SBV) disease emerged in Europe in 2011, with the virus initially identified in Germany, and the first confirmed case of SBV infection in Ireland diagnosed in a dairy calf in October 2012. SBV was subsequently confirmed by RT-PCR in 49 cattle herds and 39 sheep flocks. While these studies provide a good representation of the spatial distribution of SBV in Ireland, they do not quantify the impact of SBV on productivity. The objectives of this study were to assess the impact of SBV on weaning rate in Irish sheep flocks, based on data reported by Irish sheep farmers, and to evaluate weaning rate in sheep flocks as an indicator to be used in emerging disease surveillance systems. A questionnaire on productivity and management practices in sheep flocks was developed to gather data from sheep farmers. Valid responses from 267 sheep farmers were received. Negative binomial regression indicated that flocks with a confirmed SBV diagnosis had a weaning rate 0.9 times that of flocks free of SBV. The 10% reduction in weaning rates as a result of SBV is a justifiable concern for farmers and should be considered in formulating flock breeding policy. This study shows the value of a production database as an indicator of an emerging disease and the economic impact of that disease in Irish sheep flocks.

High spread of Schmallenberg virus among roe deer (Capreolus capreolus) in Spain

Schmallenberg virus (SBV) is an emergent virus in northwestern Europe since 2011. We conducted this study to evaluate the spread of this virus in a wild ruminant community. During 2013 and 2014, 75 serum samples of roe deer were collected from different locations of the Spanish geography and analysed for the presence of antibodies. The results revealed a widespread exposure to SBV, as well as a high seroprevalence (53.3%, CI95% 42.16–64.18). These findings demand more research with regard to the impact of SBV on roe deer health and the interactions with livestock. Results also show this species as potentially suitable for monitoring the spread of the virus through sylvatic areas.

Productive and reproductive performances of dairy cattle herds in Treviso province, Italy (2009-2012): an assessment of the potential impact of Schmallenberg virus epidemic.

BackgroundSchmallenberg virus (SBV) has spread across Europe since mid-2011, causing unspecific and transitory symptoms in ruminants and congenital malformations in their offspring. Evidence for the impact of SBV on cattle (re)productive performance is limited. Using a comprehensive data set from a SBV-affected province in North-East Italy, this study aimed at assessing the potential impact of SBV emergence on 11 productive and reproductive performance indicators of dairy cattle herds, accounting for weather conditions and other herd-level factors that could also influence these indicators.ResultsA total of 127 farms with an average of 71 cows per farm (range 29–496) were monitored monthly from January 2009 to June 2012. Mixed-effects linear models for longitudinal data were used to assess the average variation in herds’ performance indicators over semesters (Jan-Jun 2009, Jul-Dec 2009, Jan-Jun 2010, Jul-Dec 2010, Jan-Jun 2011, Jul-Dec 2011, Jan-Jun 2012) and trimesters therein. Taking the second semester of 2011 as reference, significant decreases in the average lactation length (−6 days, on average) and calving-to-conception interval (−4 days, on average) were observed relative to the same semesters of the years 2010 and 2009, respectively. Similarly, during the last trimester of 2011, which is most likely to cover the SBV infection period in the study area, there was an average decrease of −4 days (lactation length) and −7 days (calving-to-conception interval) compared to the same trimesters of the years 2010 and 2009, respectively. However, the observed decreases actually represent a positive outcome that is not as such imputable to SBV emergence, but rather reflects other beneficial changes in farm management. None of the other indicators showed significant variations, confirming the relatively mild expression of SBV infection in cattle.ConclusionsAlthough the emergence of SBV might have significantly affected the (re)productive performance of some individual farms, we concluded that overall at the province level there were no significant variations attributable to SBV, at least not in a way that would lead to negative effects on farm profitability.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0527-1) contains supplementary material, which is available to authorized users.

Schmallenberg Virus in Belgium: Estimation of Impact in Cattle and Sheep Herds.

Schmallenberg virus (SBV) emerged during summer 2011. SBV induced an unspecific syndrome in cattle and congenital signs (abortions, stillbirths and malformations) in domestic ruminants. To study the impact of SBV in Belgium, a phone survey was conducted upon September 2012. Hereto two groups of cattle farmers (A and B) and two groups of sheep farmers (C and D) were randomly selected. Farms from groups A (n=53) and C (n=42) received SBV-positive result at RT-PCR in the Belgian National Reference Laboratory (NRL). Farms from groups B (n=29) and D (n=44) never sent suspected samples to NRL for SBV analysis but were however presumed seropositive for SBV after the survey. Questionnaires related to reproduction parameters and clinical signs observed in newborn and adult animals were designed and addressed to farmers. As calculated on a basis of farmers' observations, 4% of calves in group A and 0.5% in group B were reported aborted, stillborn or deformed due to SBV in 2011-2012. The impact as observed by sheep farmers was substantially higher with 19% of lambs in group C and 11% in group D that were reported aborted, stillborn or deformed due to SBV in 2011-2012. Interestingly, abortions or stillbirths were not clear consequences of SBV outbreak in cattle farms, and the birth of a deformed animal was an essential condition to suspect SBV presence in cattle and sheep farms. This study contributes to a better knowledge of the impact of the SBV epidemic. The results suggest that SBV impacted Belgian herds mostly by the birth of deformed calves, stillborn lambs and deformed lambs. This work also demonstrates that the birth of a deformed calf or lamb was a trigger for the farmer to suspect the presence of SBV and send samples to NRL for further analyses.

Integration of production and financial models to analyse the financial impact of livestock diseases: a case study of Schmallenberg virus disease on British and French dairy farms

Aims and objectivesThe aim of the study was to investigate and compare the financial impact of Schmallenberg disease for different dairy production types in the United Kingdom and France.Materials and...

Impact of Schmallenberg virus on British farms

OVER recent years, several viruses transmitted by Culicoides midges have emerged in European livestock, leading to significant economic losses. For example, in 2006, bluetongue virus (BTV) serotype 8 emerged in...

Schmallenberg virus epidemic: Impact on milk production, reproductive performance and mortality in dairy cattle in the Netherlands and Kleve district, Germany

Schmallenberg virus (SBV), a novel orthobunyavirus that rapidly spread throughout north-western Europe in 2011, caused congenital malformations in lambs and goat kids (Van den Brom et al., 2012) and newborn calves (Hoffmann et al., 2012). The impact of the SBV epidemic seemed limited however, in terms of the number of affected herds with malformed offspring (European Food Safety Authority, 2012b). Nevertheless, little is known with regard to the overall within-herd impact of SBV infection. The objective of the current study was to quantify the impact of the 2011 SBV epidemic on the productivity of dairy cattle in the Netherlands and the district of Kleve, Germany.For the Netherlands, several multilevel multivariable statistical models were applied on eight productivity parameters regarding milk production, reproductive performance and mortality. All four fertility parameters analysed were slightly but significantly reduced between August 1st and November 1st 2011 compared to the reference period in 2009–2010. Between August 15th and September 19th 2011, the average loss in milk production per cow was −0.26kg (95% CI: −0.30; −0.22) per day in dairy herds, compared to the reference period (p<0.001). The total loss per cow in a subgroup of dairy herds that notified malformations in newborn calves during the mandatory notification period in the Netherlands was −0.43kg (95% CI: −0.59; −0.28) per day (p<0.001).For Germany, a study was carried out in the district of Kleve, situated in the state of North Rhine-Westphalia near the Dutch border. Data on milk yield, two fertility parameters and the number of rendered calves in this specific region were analysed. There was a small but significant increase in the number of secondary and third inseminations between August 1st and November 1st 2011, indicating reduced fertility. No significant change in calf mortality was observed in the assumed SBV period. Milk production at district level did not seem to be affected by SBV in August and September 2011.SBV had no or limited impact on mortality rates, which was as expected given the relatively mild expression of SBV in adult cows and the low incidence of notified malformations in newborn calves. Our results indicate that SBV had a limited impact on productivity of dairy cattle. However, the total economic impact of SBV on the ruminant industry not only consists of productivity caused losses; it is expected that international trade restrictions formed a larger part of the total economic impact.

Impact of Schmallenberg virus on British sheep farms during the 2011/2012 lambing season

British sheep farmers were invited to complete a questionnaire about the impact of Schmallenberg virus (SBV) on animal health, welfare and their own emotional wellbeing during the 2011–2012 lambing season,...

The Schmallenberg virus epidemic in Europe—2011–2013

During the Schmallenberg virus (SBV) epidemic, the European Food Safety Authority (EFSA) collected data on SBV occurrence across Europe in order to provide an assessment of spread and impact. By May 2013, twenty-nine countries were reporting to EFSA and twenty-two countries had reported cases of SBV. The total number of SBV herds reported was 13,846 and the number of SBV laboratory confirmed herds was 8730. The surveillance activities were based on the detection of SBV clinical cases (either adults or newborns). Malformation in newborns was the most commonly reported clinical sign of SBV-infection. All countries were able to provide the date when the first suspicion of SBV in the herd was reported and nineteen could report the location of the herd at a regional level. This allowed the spread of SBV in Europe to be measured both temporally and spatially. The number of SBV confirmed herds started to increase in December 2011 and two peaks were observed in 2012 (February and May). Confirmed herds continued to be reported in 2012 and into 2013. An increase during winter 2012 and spring 2013 was again observed, but the number of confirmed herds was lower than in the previous year. SBV spread rapidly throughout Europe from the initial area of detection. SBV was detected above the latitude of 60° North, which exceeds the northern expansion observed during the bluetongue virus serotype 8 epidemic in 2006–2009. The impact of SBV was calculated as ratio of the number of herds with at least one malformed SBV positive foetus and the total number of herds in this region. The 75th percentile of the malformations ratio in the various affected countries for the whole reporting period was below 1% and 3% for cattle and sheep herds, respectively. International data collection on emerging diseases represents a challenge as the nature of available data, data quality and the proportion of reported cases may vary widely between affected countries. Surveillance activities on emerging animal diseases are often structured only for case detection making the estimation of infection/diseases prevalence and the investigation of risk factors difficult. The impact of the disease must be determined to allow risk managers to take appropriate decisions. Simple within-herd impact indicators suitable for emerging disease outbreaks should be defined that could be measured as part of routine animal health surveillance programmes and allow for rapid and reliable impact assessment of emerging animal health diseases.

Schmallenberg virus in Dutch dairy herds: Potential risk factors for high within-herd seroprevalence and malformations in calves, and its impact on productivity

In November 2011, the new orthobunyavirus Schmallenberg virus (SBV) was identified in dairy cows that had induced fever, drop in milk production and diarrhoea in the Netherlands (Muskens et al., 2012. Tijdschrift voor Diergeneeskunde 137, 112–115) and a drop in milk production in cows in Northwestern Germany (Hoffmann et al., 2012. Emerging Infectious Diseases 18 (3), 469–472), in August/September 2011. This study aimed at quantifying risk factors for high within-herd prevalence of SBV and SBV-induced malformations in newborn calves in dairy herds in the Netherlands. Additionally, the within-herd impact of SBV infection on mortality rates and milk production was estimated.A case-control design was used, including 75 clinically affected case herds and 74 control herds. Control herds were selected based on absence of malformations in newborn calves and anomalies in reproductive performance. SBV-specific within-herd seroprevalences were estimated. Risk factors for high within-herd SBV seroprevalence (>50%) and the probability of malformed newborn calves in a herd were quantified. In addition, within-herd impact of SBV with regard to milk production and mortality was estimated.Animal-level seroprevalence was 84.4% (95% confidence interval (CI): 70.8–92.3) in case herds and 75.8% (95% CI: 67.5–82.5) in control herds. Control herds that were completely free from SBV were not present in the study. Herds that were grazed in 2011 had an increased odds (OR 9.9; 95% CI: 2.4–41.2)) of a high seroprevalence (>50%) compared to herds that were kept indoors. Also, when grazing was applied in 2011, the odds of malformations in newborn calves tended to be 2.6 times higher compared to herds in which cattle were kept indoors. Incidence of malformations in newborn calves at herd level was associated with both within-herd seroprevalence and clinical expression of the disease in adult cattle.The rate of vertical transmission of SBV to the fetus once a dam gets infected seemed low. A total of 146 stillborn or malformed calves were submitted by 65 farmers during the study period, of which 19 were diagnosed as SBV-positive based on pathological investigation and/or RT-qPCR testing of brain tissue. Based on these results combined with calving data from these herds we roughly estimated that at least 0.5% of the calves born between February and September 2012 have been infected by SBV.A drop in milk production was observed between the end of August 2011 and the first half of September (week 35–36), indicating the acute phase of the epidemic. During a 4-week period in which SBV infection was expected to have occurred, the total loss in milk production in affected dairy herds was around 30–51kg per cow. SBV had no or limited impact on mortality rates which was as expected given the relatively mild expression of SBV in adult cows and the low incidence of malformations in newborn calves.

Preliminary Survey on the Impact of Schmallenberg Virus on Sheep Flocks in South of Belgium

Between late February and May 2012, a preliminary anonym survey was conducted among sheep farmers in south of Belgium in order to contribute to future estimations of the economic losses caused by Schmallenberg virus (SBV). Based on clinical signs consistent with SBV infection, this survey involved 13 meat sheep flocks considered as positive flocks with subsequent SBV detection by RT-qPCR [SBV-positive flocks (PF); total of 961 animals], and 13 meat sheep flocks considered as negative flocks (NF; total of 331 animals). These preliminary results indicated several significant characteristics that were more present in PF than in NF. These include an increased rate of abortions (6.7% in PF versus 3.2% in NF), of lambs born at term but presenting malformations (10.1% in PF versus 2.0% in NF) and of dystocia (10.1% in PF versus 3.4% in NF). Lamb mortality during the first week of life was reported more frequently in PF (8 of 13 PF, 61.5%) than in NF (1 of 13 NF, 7.7%). In PF, the observed prolificacy rate was 2-fold lower (93%) than expected (186%). The implementation of a survey at larger scale, including a high number of breeders, is necessary to allow a more detailed analysis of the SBV impact in the sheep sector.

“Schmallenberg” virus: Analysis of the Epidemiological Data and Assessment of Impact

This scientific report provides an overall assessment of the impact of the infection on animal health, animal production and animal welfare of the provisionally named “Schmallenberg” virus (SBV) first detected in Germany. In Europe, 3745 holdings have been reported with SBV cases confirmed by laboratory testing across several Member States, mid May 2012. EFSA reviewed the epidemiological reports noting that SBV has been detected in cattle, sheep, goats and a bison. SBV antibodies have been detected in deer and no other species are known to be affected. EFSA also confirms that new studies support the initial assessment undertaken by the European Center for Disease Control and Prevention, that it is very unlikely that SBV poses a risk to humans. In terms of transmission routes, recent entomological investigations have identified SBV in field samples of biting midges of the Culicoides obsoletus group. Currently there is no evidence of any other route of transmission other than transplacental or vector borne routes. EFSA coordinated the collation of SBV epidemiological data during 2011–2012 in order to obtain comparable data for Europe. The maximum proportion of reported sheep holdings with SBV confirmed was 4% per country and 7.6% per region while for cattle less than 1.3 % of holdings were reported as SBV confirmed at both country and regional level. In order to assess the impact of SBV(spatial and temporal spread, proportion of affected holding and potential projection of arthrogryposis hydranencephaly syndrome cases) three models were used. In regions with SBV confirmed holdings, assuming a high prevalence of infection and post infection immunity, impact in the 2012–2013 calving and lambing season should be low. However, assuming SBV survived the winter of 2011, the models suggest that in unaffected regions with suitable temperatures for within herd transmission by vectors and high density of susceptible species (cattle and sheep) SBV infection is likely to spread. EFSA puts forward a number of recommendations to fill the knowledge gaps, these include but are not limited to: continuing serological investigations in affected regions and regions neighbouring affected areas, within herd and animal level impact investigation, monitoring putative vector population, setting SBV host vector transmission parameters, investigating other routes of transmission, host susceptibility, virulence and vulnerable period during gestation. Furthermore, the possible origins of the virus should be investigated as more information becomes available on the virus characteristics and infection epidemiology.