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1.
The Aujeszky's disease virus (ADV) eradication campaign in The Netherlands is based on compulsory vaccination and certification of ADV-free herds and consists of three stages: reduction of transmission of ADV, tracing and elimination of remaining sources of ADV, and, in the last stage prohibition of vaccination. This paper summarizes the progress made in the first two stages of the eradication. Between 1994-1999, ADV seroprevalence decreased sharply in all four regions in The Netherlands, both in the sow and the finishing pig population. In the sow population, the mean ADV prevalence in the northern, eastern and western regions decreased to less than 0.5% in the first quarter of 1998, and to approximately 1% in the southern region. For the finishing pig population, the mean ADV prevalence decreased to less than 0.6% in all four regions in the first quarter of 1998. The proportion of sow herds that were certified ADV-free increased steadily from approximately 40% in the last quarter of 1996 to 96% in the first quarter of 1999. The proportion of finishing pig herds that were certified ADV-free showed the same spectacular increase as in the sow population: from approximately 14% in the last quarter of 1996 to 90% in the first quarter of 1999. It is anticipated that the last stage of the ADV eradication campaign, stopping vaccination, will be achieved very soon. Monitoring wild boars for ADV between 1994 and 1999 indicated that ADV is uncommon within the wild boar population. Therefore, it seems that ADV infection in the wild boar population is not an important reservoir in The Netherlands.  相似文献   

2.
West Nile virus (WNV) and Usutu virus (USUV) are arboviruses that are maintained in enzootic transmission cycles between mosquitoes and birds and are occasionally transmitted to mammals. As arboviruses are currently expanding their geographic range and emerging in often unpredictable locations, surveillance is considered an important element of preparedness. To determine whether sera collected from resident and migratory birds in the Netherlands as part of avian influenza surveillance would also represent an effective source for proactive arbovirus surveillance, a random selection of such sera was screened for WNV antibodies using a commercial ELISA. In addition, sera of jackdaws and carrion crows captured for previous experimental infection studies were added to the selection. Of the 265 screened serum samples, 27 were found to be WNV–antibody‐positive, and subsequent cross‐neutralization experiments using WNV and USUV confirmed that five serum samples were positive for only WNV‐neutralizing antibodies and seven for only USUV. The positive birds consisted of four Eurasian coots (Fulica atra) and one carrion crow (Corvus corone) for WNV, of which the latter may suggest local presence of the virus, and only Eurasian coots for USUV. As a result, the screening of a small selection of serum samples originally collected for avian influenza surveillance demonstrated a seroprevalence of 1.6% for WNV and 2.8% for USUV, suggesting that this sustained infrastructure could serve as a useful source for future surveillance of arboviruses such as WNV and USUV in the Netherlands.  相似文献   

3.
The objective of this paper is to describe the severe epidemic of classical swine fever (CSF) in The Netherlands in 1997–1998 under a policy of non-vaccination, intensive surveillance, pre-emptive slaughter and stamping out in an area which has one of the highest pig and herd densities in Europe.

The primary outbreak was detected on 4 February 1997 on a mixed sow and finishing pig herd. A total of 429 outbreaks was observed during the epidemic, and approximately 700 000 pigs from these herds were slaughtered. Among these outbreaks were two artificial insemination centres, which resulted in a CSF-suspect declaration of 1680 pig herds (mainly located in the southern part of The Netherlands). The time between introduction of CSF virus (CSFV) into the country and diagnosis of CSF in the primary outbreak was estimated to be approximately 6 weeks. It is presumed that CSFV was spread from The Netherlands to Italy and Spain via shipment of infected piglets in the beginning of February 1997, before the establishment of a total stand-still of transportation. In June 1997, CSFV is presumed to be introduced into Belgium from The Netherlands.

Pre-emptive slaughter of herds that had been in contact with infected herds or were located in close vicinity of infected herds, was carried out around the first two outbreaks. However, this policy was not further exercised till mid-April 1997, when pre-emptive slaughter became a standard operational procedure for the rest of the epidemic. In total, 1286 pig herds were pre-emptively slaughtered. (approximately 1.1 million pigs). A total of 44 outbreaks (10%) was detected via pre-emptive slaughter.

When there were clinical signs, the observed symptoms in infected herds were mainly atypical: fever, apathy, ataxia or a combination of these signs. In 322 out of 429 outbreaks (75%), detection was bases on clinical signs observed: 32% was detected by the farmer, 25% by the veterinary practitioner, 10% of the outbreaks by tracing teams and 8% by screening teams of the veterinary authorities. In 76% of the outbreaks detected by clinical signs, the farmer reported to have seen clinical symptoms for less than 1 week before diagnosis, in 22% for 1–4 weeks before diagnosis, and in 4 herds (1%) the farmer reported to have seen clinical symptoms for more than 4 weeks before diagnosis.

Transportation lorries played a major role in the transmission of CSFV before the primary outbreak was diagnosed. It is estimated that approximately 39 herds were already infected before the first measures of the eradication campaign came into force.

After the first measures to stop the spread of CSFV had been implemented, the distribution of the most likely routes of transmission markedly changed. In most outbreaks, a neighbourhood infection was indicated.

Basically, there were two reasons for this catastrophe. Firstly, there was the extent of the period between introduction of the virus in the region and detection of the first outbreak. As a result, CSFV had opportunities to spread from one herd to another during this period. Secondly, the measures initially taken did not prove sufficient in the swine- and herd-dense region involved.  相似文献   


4.
Since January 2, 2001 a large-scale active surveillance programme for BSE started in the Netherlands in addition to the passive surveillance programme of cattle with clinical symptoms compatible with BSE. Based on decisions of the Council of European Ministers of Agriculture, the European Union launched an active surveillance system for BSE in cattle of 30 months and older. Until April 1, more than 100,000 head of cattle were tested in this scheme, including all cattle slaughtered and a large part of the cattle that died on the farm. Four animals were found positive in the active surveillance system and one cow from the passive surveillance tested positive for BSE during the first three months.  相似文献   

5.
Salmonella enteritidis was identified by serological and bacteriological techniques in two clinically normal breeder flocks in an integrated broiler organisation in Northern Ireland. The organism was transmitted vertically to clinically affected progeny flocks. The infected breeder flocks were slaughtered and the infection throughout the organisation controlled and subsequently eradicated. A working group, consisting of the senior management of the broiler organisation and veterinary staff from the Veterinary Research Laboratories at Stormont, was formed to establish procedures to minimise the risk of the reintroduction of salmonella infection, by preventing vertical transmission from grandparent flocks, or lateral transmission from personnel, other animal species and fomites, or transmission through the feed. All feed was heated to a minimum of 70 degrees C for 12 minutes immediately before it was pelleted and subsequently transported to the flocks through a dedicated system of conveyor belts, bins and lorries. A comprehensive system for monitoring the efficacy of the preventive procedures was established and is now used throughout the poultry industry of Northern Ireland.  相似文献   

6.
The Netherlands holds the bovine tuberculosis-free (BTB-free) status according to European Union standards, but in recent years small outbreaks of the infection have occurred. After the last outbreak in 1999 with 10 infected herds the question raised if the current surveillance system, visual inspection of carcasses at the slaughterhouse, is efficient enough to detect infected cattle in time and to maintain the official BTB-free status.

Through epidemiological modelling, the risk of a major outbreak is quantified, using one of six surveillance strategies. These are the currently used visual inspection of carcasses at the slaughterhouse (SL), the ELISA test on blood samples of carcasses at the slaughterhouse (ELISA-B), the γ-interferon test on blood samples of carcasses at the slaughterhouse (GAMMA-B), comparative tuberculination of the herd (CT), the combined method of single and comparative tuberculination of the herd (ST + CT) and the ELISA test on samples of bulk milk (ELISA-M). Test frequency of the last three methods was varied as well.

A stochastic individual based model (IBM) was developed to simulate a chain of infected herds, where each individual animal is followed in time. The model mimics the nation-wide situation after the introduction of one infected animal into one herd. BTB-transmission is simulated with an S-E1-E2-I state transition model. Output is time until detection of the infection, prevalence in the detected herd and the number of infected herds at the time of detection. For the assessment 500 simulations were used, representing 500 BTB-introductions. Model robustness to parameter values was analysed with Monte Carlo elasticity analysis, for which 1000 simulations were used.

Results of median time until detection and median number of infected farms at detection for SL (302 weeks and seven farms) were in agreement with estimates from an outbreak in the Netherlands in 1999. ELISA-B and GAMMA-B performed better than SL with a much lower median time until detection (189 and 97 weeks, respectively). The results for the tuberculination methods (ST + CT and CT) and ELISA-M depended heavily on the frequency in which the tests were performed. The tuberculination methods ST + CT and CT yield comparable results and detect the infection sooner than SL, also at the lowest tested frequency of once in 5 years. ELISA-M is comparable with SL at frequencies of once in 4 or 5 years, and this test works well at frequencies of once a year or higher. Our study results are used for an economical optimisation analysis of the six surveillance strategies.  相似文献   


7.
In this study, we have analyzed 23 PCV2 ORF2 sequences recovered from wild boar population in Romania. The PCV2 sequences were originated from different geographical regions in Romania, and collected between 2008 and 2009 during the classical swine fever virus (CSFV) surveillance campaign. Complete open reading frame 2 (ORF2) nucleotide sequences were obtained and compared with sequences mainly from European and Asian isolates. The Romanian sequences were identified as belonging to previously described clusters 2a and 2b, with high degree of heterogeneity (PCV2 ORF2 nucleotide homology ranged between 90.1% and 100%). Interestingly, for cluster 2a, the majority of the sequences (8 from a total number of 9) clustered mainly with the Asian isolates (especially China, but also India and South Korea), with three exceptions from Europe previously reported in Germany, Belgium and The Netherlands.  相似文献   

8.
In this study, we have analyzed 23 PCV2 ORF2 sequences recovered from wild boar population in Romania. The PCV2 sequences were originated from different geographical regions in Romania, and collected between 2008 and 2009 during the classical swine fever virus (CSFV) surveillance campaign. Complete open reading frame 2 (ORF2) nucleotide sequences were obtained and compared with sequences mainly from European and Asian isolates. The Romanian sequences were identified as belonging to previously described clusters 2a and 2b, with high degree of heterogeneity (PCV2 ORF2 nucleotide homology ranged between 90.1% and 100%). Interestingly, for cluster 2a, the majority of the sequences (8 from a total number of 9) clustered mainly with the Asian isolates (especially China, but also India and South Korea), with three exceptions from Europe previously reported in Germany, Belgium and The Netherlands.  相似文献   

9.
The 1997-1998 epidemic of classical swine fever in the Netherlands   总被引：9，自引：0，他引：9  
In 1997, the pig husbandry in the Netherlands was struck by a severe epidemic of classical swine fever (CSF). During this epidemic 429 CSF-infected herds were depopulated and approximately 1300 herds were slaughtered pre-emptively. In addition millions of pigs of herds not CSF-infected were killed for welfare reasons (over crowding or overweight). In this paper, we describe the course of the epidemic and the measures that were taken to control it.The first outbreak was detected on 4 February 1997 in the pig dense south-eastern part of the Netherlands. We estimate that CSF virus (CSFV) had already been present in the country by that time for 5-7 weeks and that the virus had been introduced into approximately 39 herds before the eradication campaign started. This campaign consisted of stamping-out infected herds, movement restrictions and efforts to diagnose infected herds as soon as possible. However, despite these measures the rate at which new outbreaks were detected continued to rise. The epidemic faded out only upon the implementation of additional measures such as rapid pre-emptive slaughter of herds in contact with or located near infected herds, increased hygienic measures, biweekly screening of all herds by veterinary practitioners, and reduction of the transportation movements for welfare reasons. The last infected herd was depopulated on 6 March 1998.  相似文献   

10.
For the eradication of an infectious agent, like bovine herpesvirus 1 (BHV-1), surveillance and certification can be used to reduce the transmission between herds. The goal of surveillance is that a certified herd that becomes infected is detected timely so that infection of several other certified herds is prevented. What counts is whether the reproduction ratio R, i.e. the average number of certified herds infected by one infected certified herd can be kept below 1. To support policy makers in making decisions about the minimal demands for a surveillance programme in an eradication campaign of BHV-1 in cattle, two mathematical models were investigated. With these models, the basic reproduction ratio between herds was calculated. The surveillance programmes were characterised with sample size, sampling frequency, test sensitivity, herd size, vaccination status, and contacts between herds. When R between herds is below 1, then the surveillance programme is sufficiently good to prevent spread of infection, provided that R is estimated well. In the model based on bulk milk testing sample size was replaced by a threshold at which bulk milk can be found positive. The R between herds was mainly influenced by the vaccination status, sampling frequency, and contacts between herds. Herd size moderately affected the outcome. Test sensitivity and sample size, however, were of minor importance. If herds of 50 cows became free of BHV-1 without vaccination, then spread of infection between herds might be prevented when animals within herds are sampled once a year (milk or blood samples). This frequency needs to be intensified, being twice a year, for larger herds and/or herds with extensive contacts with other herds. When bulk milk is sampled instead, sampling should be done at least every 5 months and more intensively, being each month, with larger herd sizes and more contacts between herds.  相似文献   

11.
We constructed a stochastic bio-economic model to determine the optimal cost-efficient surveillance program for bovine tuberculosis. The surveillance programs differed in combinations of one or more detection methods and/or sampling frequency. Stochastic input variables in the epidemiological module described the dynamics of infection and the probability of detection. By means of an efficiency frontier, the trade-off between the expected cost and the epidemiological risk parameter relating to the outbreak size was evaluated. The surveillance scheme based on visual inspection of lesions on carcasses at slaughter was optimal given the current prevalence of the disease in the Netherlands if the objective was to minimise the expected costs. However, the efficient set also included two other schemes: slaughterhouse inspection in combination with GAMMA-interferon testing of blood samples and slaughterhouse inspection in combination with two-stage tuberculin testing. The choice ultimately will depend on the risk attitude of the decision-maker; a more-stringent surveillance scheme will be enforced if the expected outbreak size is to be constrained. In future scenarios, ELISA testing of bulk-tank milk in combination with the current slaughterhouse inspection procedure would outperform the surveillance scheme of solely slaughterhouse inspection if ELISA testing of bulk-tank milk becomes feasible.  相似文献   

12.
In March 2007, cutaneous nodules were observed on the neck, shoulder and back of a breeding bull imported from France in November 2006. The nodules opened spontaneously and produced a haemorrhagic exudate. The cause was Parafilaria bovicola, a filariid nematode not endemic to The Netherlands. The worm can cause substantial economic loss because of the need to trim carcasses and because of the diminished value of hides. The infection is spread by the fly Musca autumnalis, which is common in The Netherlands. Because treatment does not stop the infection from spreading, the bull was culled to prevent the risk of infection of the national herd. To our knowledge, this is the first case of Parafilaria bovicola in The Netherlands.  相似文献   

13.
The paper reviews the eradication of bovine tuberculosis from Australia with special reference to surveillance and managing the risk of animals exposed to tuberculosis infected animals during the latter stages of eradication. The successful eradication was based on a sound technical program with strong industry and government support. The model of joint industry and government funding and decision-making first used during the brucellosis and tuberculosis eradication campaign (BTEC) has been successfully incorporated within subsequent livestock disease control programs in Australia. An overview of the history of tuberculosis eradication in Australia provides a background to the surveillance approach. Australia was fortunate that there were no wildlife reservoir hosts. Feral animal reservoir hosts were removed during the eradication program. Surveillance to detect rare diseases is recognised to be statistically challenging with high resource requirements. Australian veterinary authorities have a high level of confidence that the combination of increasing sensitivity of abattoir surveillance systems by the submission of all granulomas detected at slaughter with increasing risk management of animals exposed to tuberculosis infected animals during the final stages of eradication provides a high level of assurance that Mycobacterium bovis has been eradicated.  相似文献   

14.
Surveillance programmes for low pathogenicity (LPAI) and high pathogenicity avian influenza (HPAI) infections in poultry are compulsory for EU Member States; yet, these programmes have rarely been evaluated. In Italy, following a 1999 HPAI epidemic, control measures, including vaccination and monitoring, were implemented in the densely populated poultry area (DPPA) where all epidemics in Italy have been concentrated. We evaluated the monitoring system for its capacity to detect outbreaks rapidly in meat‐type turkey flocks. The evaluation was performed in vaccination areas and high‐risk areas in the DPPA, in 2000–2005, during which four epidemics occurred. Serum samples and cloacal swabs were taken from vaccinated birds and unvaccinated (sentinel) birds. We compared the detection rate of active, passive and targeted surveillance, by vaccination status, using multinomial logistic regression. A total of 13 275 samplings for serological testing and 4889 samplings for virological testing were performed; 6315 production cycles of different bird species were tested. The outbreaks detection rate in meat‐type turkeys was 61% for active surveillance (n = 222/363 outbreaks), 32% for passive surveillance and 7% for targeted surveillance. The maximum likelihood predicted values for the detection rates differed by vaccination status: in unvaccinated flocks, it was 50% for active surveillance, 40% for passive surveillance and 10% for targeted surveillance, compared to respectively 79%, 17% and 4% for vaccinated flocks. Active surveillance seems to be most effective in detecting infection, especially when a vaccination programme is in place. This is the first evaluation of the effectiveness of different types of surveillance in monitoring LPAI infections in vaccinated poultry using field data.  相似文献   

15.
Summary

Serological surveys of the prevalence of antibodies against Toxoplasma gondii were carried out amongst swine and cattle in the Netherlands. Data were analysed according to the different categories of animals. The results show very low seroprevalences of Toxoplasma gondii in finishing pigs (1.8%) and in fattening calves (1.2%). In sows and dairy cattle, respectively, seroprevalences of 30.9% and 27.9% respectively, were found, demonstrating clearly the environmental infection pressure and illustrating the importance of housing and management in establishing low infection rates.

Substantially different seroprevalences were found between dairy cattle sampled in the North and in the South of the Netherlands (13.1% and 42.6%, respectively).

The infection rates in the samples from finishing pigs, fattening calves, and dairy cattle demonstrate that seroprevalences in individual farms or herds may differ considerably. Investigation of the factors involved can be useful in determining the causes of infection and for developing measures with regard to prevention. The very low seroprevalences in finishing pigs and fattening calves indicate, however, that the production of toxoplasma‐free meat may be well within reach in modern husbandry.

Since farm animals easily are infected, serological screening of individual farms or herds for the absence of T. gondii infection, as a part of the Integrated Quality Control programme, can be helpful in determining the quality of livestock production and in developing certain standards of hygiene for individual farms.  相似文献   

16.
Bluetongue (BT) and/or BT viruses (BTV) have been identified in the Mediterranean basin and the Balkans each year from 1998 to 2002 and in particular BTV serotype 2 in the French Island of Corsica (2000 and 2001). In response to these virus incursions, the French Veterinary Authorities carried out epidemiological studies that included virological, serological and entomological analysis, and two vaccination campaigns performed in the winter of 2000/2001 and the winter and spring of 2001 and 2002. Rapid and reliable serotype differentiation is essential at the start of an outbreak to allow an early selection of vaccine to control the spread of the virus. Thus, molecular tools, that complement conventional methods, have been developed for early detection of infection, determination of the serotype, and differentiation between natural infection and vaccination. Serological results showed that the first vaccination campaign during the winter of 2000/2001 did not provide full protection for all sheep and during the summer of 2001, 335 sheep flocks in Corsica were again infected by BTV 2 (7-fold more that in 2000). Entomological studies have demonstrated that the only proven vector of the disease, Culicoides imicola, was present in the island in 2000 and that it has successfully established itself in Corsica. The safety and immunogenicity of the commercial South African vaccine were studied. Fourteen sheep were vaccinated and then observed for clinical signs. Blood, sera, spleen and lymph nodes were collected and analyzed, and the results confirmed the safety and potency of using this vaccine to protect sheep from clinical disease. As a result, an intensive vaccination campaign was performed during winter and spring 2001/2002. No cases of BT had been observed by the end of summer 2002, indicating that the vaccination campaign has been successful in protecting sheep from infection.  相似文献   

17.
From February 1997 till May 1998 the national reference laboratory for classical swine fever (CSF) in the Netherlands was confronted with millions of samples taken from pigs during an outbreak of CSF in a pig dense region. In a limited period major logistic problems needed to be solved regarding the processing of samples and information at the laboratory facilities.In total over 2.3 million samples were examined by different CSF diagnostic methods. The majority (approximately 2.1 million) of these samples were blood samples which were tested for CSF serum antibody in a semi-automated ELISA. Approximately 166,000 samples were examined for the presence of CSF virus or viral antigen. Automated preparation and testing of blood samples for CSF serum antibody, the obligatory identification and registration system of pig holdings and the computerised laboratory management system made it possible to process the huge amount of samples and information presented in a limited period. The majority of the test results was sent to the veterinary authorities via e-mail or a computerised fax system.Of the 429 outbreaks 82% were detected via a direct immunofluorescence technique performed on cryostat sections of the tonsil. The sampling of clinically suspected pigs ('guided' sampling) for this diagnostic method provided rapid positive and negative results and thus played a paramount role during the eradication campaign. Serological surveys identified 13.5% of the infected pig holdings: such surveys proved very effective in the screening of holdings which were subjected to restrictions (protection or surveillance zones) for many months. Virus isolation performed on different types of samples detected 4. 5% of the infected pig holdings.In conclusion, analysis of data collected in the laboratory and epidemiological analysis should result in an improved eradication plan for the future control of outbreaks of CSF in the Netherlands supported by optimised CSF diagnostic methods.  相似文献   

18.
Surveillance for new emerging animal diseases from a European perspective is complicated by the non-harmonised approach across Member States for data capture, recording livestock populations and case definitions. In the summer of 2011, a new vector-borne Orthobunyavirus emerged in Northern Europe and for the first time, a coordinated approach to horizon scanning, risk communication, data and diagnostic test sharing allowed EU Member States to develop early predictions of the disease, its impact and risk management options. There are many different systems in place across the EU for syndromic and scanning surveillance and the differences in these systems have presented epidemiologists and risk assessors with concerns about their combined use in early identification of an emerging disease. The emergence of a new disease always will raise challenging issues around lack of capability and lack of knowledge; however, Schmallenberg virus (SBV) gave veterinary authorities an additional complex problem: the infection caused few clinical signs in adult animals, with no indication of the possible source and little evidence about its spread or means of transmission. This paper documents the different systems in place in some of the countries (Germany and the Netherlands) which detected disease initially and predicted its spread (to the UK) and how information sharing helped to inform early warning and risk assessment for Member States. Microarray technology was used to identify SBV as a new pathogen and data from the automated cattle milking systems coupled with farmer-derived data on reporting non-specific clinical signs gave the first indications of a widespread issue while the UK used meteorological modelling to map disease incursion. The coordinating role of both EFSA and the European Commission were vital as are the opportunities presented by web-based publishing for disseminating information to industry and the public. The future of detecting emerging disease looks more positive in the light of this combined approach in the EU.  相似文献   

19.
For the first time, bluetongue has been diagnosed in goats in the Netherlands and in Northwest-Europe. On the 17th of August 2006, bluetongue was for the first time diagnosed in sheep and a little later in cattle in The Netherlands. The clinical symptoms, diagnostics and differential diagnosis of bluetongue (BT) in goats in the Netherlands are described. The most obvious clinical signs were an acute drop in milk production and high fever (up to 42 degrees C). Clinical signs were less obvious than usually seen for clinically diseased sheep and cattle. A few goats showed oedema of the lips and the head, some nasal discharge and scabs on the nose and lips. Further erythema of the skin of the udder and small subcutaneous hemorrhages were seen. Just like one year ago, for the very first suspicion of bluetongue in Northwest-Europe, a good collaboration between practitioners, specialists of the Animal Health Service (GD Deventer), the Specialist Team of the Food and Consumer Product Safety Authority (VWA), and the Central Institute for animal Disease Control (CIDC-Lelystad) in The Netherlands, led to the first and rapid notification and confirmation of the suspicion of bluetongue.  相似文献   

20.
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 30–51 kg 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.  相似文献   

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