TY - JOUR T1 - Assessment of the control measures for category A diseases of Animal Health Law: Lumpy Skin Disease JF - EFSA Journal Y1 - 2022 A1 - Søren Saxmose Nielsen A1 - Julio Alvarez A1 - Dominique Joseph Bicout A1 - Paolo Calistri A1 - Elisabetta Canali A1 - Julian Ashley Drewe A1 - Bruno Garin‐Bastuji A1 - José Luis Gonzalez Rojas A1 - Christian Gortázar Schmidt A1 - Mette Herskin A1 - Virginie Michel A1 - Miguel Ángel Miranda Chueca A1 - Barbara Padalino A1 - Paolo Pasquali A1 - Liisa Helena Sihvonen A1 - Hans Spoolder A1 - Ståhl, Karl A1 - Antonio Velarde A1 - Arvo Viltrop A1 - Christoph Winckler A1 - Kris De Clercq A1 - Gubbins, Simon A1 - Klement, Eyal A1 - Jan Arend Stegeman A1 - Sotiria‐Eleni Antoniou A1 - Inma Aznar A1 - Alessandro Broglia A1 - Yves Van der Stede A1 - Gabriele Zancanaro A1 - Helen Clare Roberts KW - disease control measures KW - LSD KW - Lumpy skin disease KW - monitoringperiod KW - protection zone KW - sampling procedures KW - surveillance zone AB -

EFSA received a mandate from the EC to assess the effectiveness of some of the control measuresagainst diseases included in the Category A list according to Regulation (EU) 2016/429 ontransmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions wherethese control measures are assessed, with this opinion covering the assessment of control measuresfor Lumpy Skin Disease (LSD). In this opinion, EFSA and the AHAW Panel of experts review theeffectiveness of: i) clinical and laboratory sampling procedures, ii) monitoring period and iii) theminimum radius of the protection and surveillance zones, and the minimum length of time thatmeasures should be applied in these zones. The general methodology used for this series of opinionshas been published elsewhere; nonetheless, the transmission kernels used for the assessment of theminimum radius of the protection and surveillance zones are shown. Several scenarios for which thesecontrol measures had to be assessed were designed and agreed prior to the start of the assessment.The monitoring period was assessed as effective, and based on the transmission kernels available, itwas concluded that the protection zone of 20 km radius and the surveillance zone of 50 km radiuswould comprise>99% of the transmission from an affected establishment if transmission occurred.Recommendations provided for each of the assessed scenarios aim to support the EuropeanCommission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests inrelation to LSD.

VL - 20 CP - 1 M3 - 10.2903/j.efsa.2022.7121 ER - TY - JOUR T1 - Improving laboratory diagnostic capacities of emerging diseases using knowledge mapping JF - Transboundary and Emerging Diseases Y1 - 2021 A1 - Mickael Cargnel A1 - Juana Bianchini A1 - Sarah Welby A1 - F. Koenen A1 - Yves Van der Stede A1 - Kris De Clercq A1 - Saegerman, Claude VL - 68 CP - 3 M3 - 10.1111/tbed.13768 ER - TY - JOUR T1 - Scientific Opinion on the assessment of the control measures for category A diseases of Animal Health Law: Foot and Mouth Disease JF - EFSA Journal Y1 - 2021 A1 - Søren Saxmose Nielsen A1 - Julio Alvarez A1 - Dominique Joseph Bicout A1 - Paolo Calistri A1 - Elisabetta Canali A1 - Julian Ashley Drewe A1 - Bruno Garin‐Bastuji A1 - José Luis Gonzalez Rojas A1 - Christian Gortázar Schmidt A1 - Mette Herskin A1 - Virginie Michel A1 - Miguel Ángel Miranda Chueca A1 - Barbara Padalino A1 - Paolo Pasquali A1 - Liisa Helena Sihvonen A1 - Hans Spoolder A1 - Ståhl, Karl A1 - Antonio Velarde A1 - Arvo Viltrop A1 - Christoph Winckler A1 - Kris De Clercq A1 - Gubbins, Simon A1 - Klement, Eyal A1 - Jan Arend Stegeman A1 - Sotiria‐Eleni Antoniou A1 - Inma Aznar A1 - Alessandro Broglia A1 - Alexandra Papanikolaou A1 - Yves Van der Stede A1 - Gabriele Zancanaro A1 - Helen Clare Roberts AB -

EFSA received a mandate from the European Commission to assess the effectiveness of some of thecontrol measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series ofopinions where these control measures will be assessed, with this opinion covering the assessmentof control measures for foot and mouth disease (FMD). In this opinion, EFSA and the AHAW Panel ofexperts review the effectiveness of: i) clinical and laboratory sampling procedures, ii) monitoring periodand iii) the minimum radius of the protection and surveillance zones, and the minimum length of timethe measures should be applied in these zones. The general methodology used for this series ofopinions has been published elsewhere; nonetheless, the transmission kernels used for the assessmentof the minimum radius of the protection zone of 3 km and of the surveillance zone of 10 km areshown. Several scenarios for which these control measures had to be assessed were designed andagreed prior to the start of the assessment. The monitoring period of 21 days was assessed aseffective, and it was concluded that the protection and the surveillance zones comprise>99% of theinfections from an affected establishment if transmission occurred. Recommendations, provided foreach of the scenarios assessed, aim to support the European Commission in the drafting of furtherpieces of legislation, as well as for plausible ad hoc requests in relation to FMD.

VL - 19 CP - 6 M3 - 10.2903/j.efsa.2021.6632 ER - TY - JOUR T1 - Scientific Opinion on the assessment of the control measures of the category A diseases of Animal Health Law: Highly Pathogenic Avian Influenza JF - EFSA Journal Y1 - 2021 A1 - Søren Saxmose Nielsen A1 - Julio Alvarez A1 - Dominique Joseph Bicout A1 - Paolo Calistri A1 - Klaus Depner A1 - Julian Ashley Drewe A1 - Bruno Garin‐Bastuji A1 - José Luis Gonzalez Rojas A1 - Schmidt, Christian Gortázar A1 - Mette Herskin A1 - Virginie Michel A1 - Miguel Ángel Miranda Chueca A1 - Paolo Pasquali A1 - Helen Clare Roberts A1 - Liisa Helena Sihvonen A1 - Hans Spoolder A1 - Ståhl, Karl A1 - Calvo, Antonio Velarde A1 - Arvo Viltrop A1 - Christoph Winckler A1 - Kris De Clercq A1 - Klement, Eyal A1 - Jan Arend Stegeman A1 - Gubbins, Simon A1 - Sotiria‐Eleni Antoniou A1 - Alessandro Broglia A1 - Yves Van der Stede A1 - Gabriele Zancanaro A1 - Inma Aznar KW - Avian Influenza KW - Control measures KW - HPAI KW - monitoring period KW - protection zone KW - sampling procedures KW - surveillance zone AB -

EFSA received a mandate from the European Commission to assess the effectiveness of some of thecontrol measures against diseases included in the Category A list according to Regulation (EU) 2016/429on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions wherethese control measures will be assessed, with this opinion covering the assessment of control measuresfor Highly Pathogenic Avian Influenza (HPAI). In this opinion, EFSA and the AHAW Panel of expertsreview the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii)the minimum radius of the protection and surveillance zone, and the minimum length of time themeasures should be applied in these zones. The general methodology used for this series of opinions hasbeen published elsewhere; nonetheless, specific details of the model used for the assessment of thelaboratory sampling procedures for HPAI are presented here. Here, also, the transmission kernels usedfor the assessment of the minimum radius of the protection and surveillance zones are shown. Severalscenarios for which these control measures had to be assessed were designed and agreed prior to thestart of the assessment. In summary, sampling procedures as described in the diagnostic manual forHPAI were considered efficient for gallinaceous poultry, whereas additional sampling is advised forAnseriformes. The monitoring period was assessed as effective, and it was demonstrated that thesurveillance zone comprises 95% of the infections from an affected establishment. Recommendationsprovided for each of the scenarios assessed aim to support the European Commission in the drafting offurther pieces of legislation, as well as for plausible ad hoc requests in relation to HPAI.

VL - 19 CP - 1 M3 - 10.2903/j.efsa.2021.6372 ER - TY - RPRT T1 - Scientific Opinion on the assessment of the control measures of the category A diseases of Animal Health Law: African Swine Fever Y1 - 2021 A1 - Søren Saxmose Nielsen A1 - Julio Alvarez A1 - Dominique Joseph Bicout A1 - Paolo Calistri A1 - Klaus Depner A1 - Julian Ashley Drewe A1 - Bruno Garin‐Bastuji A1 - José Luis Gonzalez Rojas A1 - Christian Gortázar Schmidt A1 - Mette Herskin A1 - Virginie Michel A1 - Miguel Ángel Miranda Chueca A1 - Paolo Pasquali A1 - Helen Clare Roberts A1 - Liisa Helena Sihvonen A1 - Hans Spoolder A1 - Ståhl, Karl A1 - Antonio Velarde A1 - Arvo Viltrop A1 - Christoph Winckler A1 - Kris De Clercq A1 - Klement, Eyal A1 - Jan Arend Stegeman A1 - Gubbins, Simon A1 - Sotiria‐Eleni Antoniou A1 - Alessandro Broglia A1 - Yves Van der Stede A1 - Gabriele Zancanaro A1 - Inma Aznar KW - African Swine Fever KW - disease control measures KW - Suids KW - vector borne disease AB -

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for African Swine Fever (ASF). In this opinion, EFSA and the AHAW Panel of experts reviewed the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radius of the protection and surveillance zone, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, specific details of the model used for the assessment of the laboratory sampling procedures for ASF are presented here. Here, also, the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones are shown. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. In summary, several sampling procedures as described in the diagnostic manual for ASF were considered ineffective and a suggestion to exclude, or to substitute with more effective procedures was made. The monitoring period was assessed as non-effective for several scenarios and a longer monitoring period was suggested to ensure detection of potentially infected herds. It was demonstrated that the surveillance zone comprises 95% of the infections from an affected establishment, and therefore is considered effective. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to ASF.

PB - EFSA VL - 19 CP - 1 M3 - 10.2903/j.efsa.2021.6402 ER - TY - JOUR T1 - Scientific Opinion on the assessment of the control measures of the category A diseases of Animal Health Law: African Horse Sickness JF - EFSA Journal Y1 - 2021 A1 - Søren Saxmose Nielsen A1 - Julio Alvarez A1 - Dominique Joseph Bicout A1 - Paolo Calistri A1 - Klaus Depner A1 - Julian Ashley Drewe A1 - Bruno Garin‐Bastuji A1 - José Luis Gonzalez Rojas A1 - Christian Gortázar Schmidt A1 - Mette Herskin A1 - Virginie Michel A1 - Miguel Ángel Miranda Chueca A1 - Paolo Pasquali A1 - Helen Clare Roberts A1 - Liisa Helena Sihvonen A1 - Hans Spoolder A1 - Ståhl, Karl A1 - Antonio Velarde A1 - Arvo Viltrop A1 - Christoph Winckler A1 - Kris De Clercq A1 - Klement, Eyal A1 - Jan Arend Stegeman A1 - Gubbins, Simon A1 - Sotiria‐Eleni Antoniou A1 - Alessandro Broglia A1 - Yves Van der Stede A1 - Gabriele Zancanaro A1 - Inma Aznar KW - African Horse Sickness KW - Equidae KW - Keywords:Disease control measures KW - monitoring period KW - protection and surveillance zones KW - sampling procedures KW - vector borne disease AB -

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for African Horse Sickness (AHS). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radius of the protection and surveillance zone, and the minimum duration of measures in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, specific details of the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones are shown. Several scenarios for which these control measures were assessed were designed and agreed prior to the start of the assessment. In summary, sampling procedures described in the diagnostic manual for AHS were considered efficient for all Equidae considering the high case fatality rate expected. The monitoring period (14 days) was assessed as effective in every scenario, except for those relating to the epidemiological enquiry where the risk manager should consider increasing the monitoring period, based on the awareness of keepers, environmental conditions and the vector abundance in the region. The current protection zone (100 km) comprises more than 95% of the infections from an affected establishment. Both the radius and duration of the zones could be reduced, based on local environmental conditions and the time of year of the first index case. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation relating to AHS.

VL - 19 CP - 2 M3 - 10.2903/j.efsa.2021.6403 ER - TY - JOUR T1 - Prioritization of livestock transboundary diseases in Belgium using a multicriteria decision analysis tool based on drivers of emergence JF - Transboundary and Emerging Diseases Y1 - 2020 A1 - Juana Bianchini A1 - Marie‐France Humblet A1 - Mickael Cargnel A1 - Yves Van der Stede A1 - F. Koenen A1 - Kris De Clercq A1 - Saegerman, Claude VL - 67 CP - 1 M3 - 10.1111/tbed.13356 ER - TY - JOUR T1 - Effectiveness and cost‐benefit study to encourage herd owners in a cost sharing vaccination programme against bluetongue serotype‐8 in Belgium JF - Transboundary and Emerging Diseases Y1 - 2019 A1 - Mickael Cargnel A1 - Yves Van der Stede A1 - Andy Haegeman A1 - Ilse De Leeuw A1 - Kris De Clercq A1 - Estelle Méroc A1 - Sarah Welby VL - 66 CP - 1 M3 - 10.1111/tbed.13034 ER - TY - JOUR T1 - The Assessment of African Swine Fever Virus Risk to Belgium Early 2014, using the Quick and Semiquantitative Pandora Screening Protocol. JF - Transbound Emerg Dis Y1 - 2017 A1 - Sophie Roelandt A1 - Yves Van der Stede A1 - D'hondt, B A1 - F. Koenen KW - African Swine Fever KW - African Swine Fever Virus KW - Animals KW - Belgium KW - Disease Outbreaks KW - Mass Screening KW - Risk Assessment KW - Swine AB -

A risk assessment was organized during the early EU ASF outbreaks of early 2014 (February-April) and performed in cooperation with 15 Belgian and European experts on ASFV and its epidemiology in pigs/wild boar. African swine fever (ASF) is considered as one of the most dangerous infectious pig diseases, causing many outbreaks. Since the end of 2013 - early 2014, several outbreaks within the European Union (Lithuania, Poland, Estonia and Latvia) were reported to OIE, which prompted several risk assessments by (inter)national bodies and scientists. In this study, the open source, semiquantitative Pandora risk assessment tool was used for a quick overall screening of the risk posed by ASF to Belgium early 2014. A set of integrated risk scores was calculated within the Pandora framework. Experts scored the questions and uncertainty levels in the Pandora modules individually, after which the calculations were performed and averaged scores were used within pre-defined risk scales to define and visualize the ASF risk to Belgium. Emergence risk was considered low (Pandora score 0.29), while disease consequences were deemed high (0.93); the resulting multiplicative overall risk of ASFV for Belgium was low (0.27). The Belgian experts tended to give lower risk scores than the European experts, especially for entry risk and trade/public opinion consequences. These risk scores are further interpreted with a due consideration of the qualitative data in the expert remarks and of other ASF risk assessments. The results are similar to more extensive and elaborate risk assessment models/procedures which may require more time and resources. The Pandora tool allows sequential updates to monitor (rates of) increasing risk and provides information for risk managers to organize targeted control.

VL - 64 CP - 1 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25939453?dopt=Abstract M3 - 10.1111/tbed.12365 ER - TY - JOUR T1 - Comparative Tick-Borne Encephalitis (Virus) Surveillance in Belgium 2009-2015: Experiences with Diagnostic Tests, Sentinel Species and Surveillance Designs JF - Journal of Zoonotic Diseases and Public Health Y1 - 2017 A1 - Sophie Roelandt A1 - Vanessa Suin A1 - Steven Van Gucht A1 - Yves Van der Stede A1 - S. Roels KW - Tick-borne encephalitis (virus); Wild boar; Roe deer; Sentinel species; AB -

When it is not overtly affecting human beings, the Tick-Borne Encephalitis Flavivirus (TBEV) remains mostly unnoticed during its enzootic cycles within vectors and unaffected animal species. Until recently, Belgium was “presumed” free of this important neuro-pathogenic virus without any scientific substantiation. Nonetheless, Belgium is clearly at risk of Tick-Borne Encephalitis (TBE) emergence

and incursions from endemic zones in the neighboring countries. This comparative review paper describes 5 Belgian veterinary serological studies with enzyme-linked immunosorbent assays and seroneutralisation tests (ELISA/SNT), in which several surveillance schemes were used (active/passive, risk-/laboratory-/range-based) in classic TBE sentinel species (dogs, cattle, roe deer, wild boar). Additionally, passive syndromic surveillance in two medical laboratories resulted in inconclusive medical data. Details are given on the scientists’ experiences with available first/second line diagnostic tests and with the different surveillance methods/survey designs. Each of the veterinary studies clearly demonstrated the presence of TBEV-specific antibodies in Belgian sentinels, sometimes even at high seroneutralisation (SNT) titers, while the medical data remain so far inconclusive, despite positive

reactions of some patients in some TBEV-tests. These results have substantiated our suspicion of TBEV-presence in Belgium from 2010 onwards and have allowed sentinel comparisons based on “suitability criteria”. Furthermore, the studies have highlighted the need for further veterinary validation of commercial ELISA tests in comparison to the gold standard SNT.

VL - 1 CP - 4 M3 - http://www.imedpub.com/articles/comparative-tickborne-encephalitisvirus-surveillance-in-belgium-20092015experiences-with-diagnostic-tests-sentinelspecies-and-surv.php?aid=19858 ER - TY - JOUR T1 - Effectiveness and Cost Efficiency of Different Surveillance Components for Proving Freedom and Early Detection of Disease: Bluetongue Serotype 8 in Cattle as Case Study for Belgium, France and the Netherlands. JF - Transbound Emerg Dis Y1 - 2017 A1 - Sarah Welby A1 - van Schaik, G A1 - Veldhuis, A A1 - Brouwer-Middelesch, H A1 - Peroz, C A1 - Santman-Berends, I M A1 - Fourichon, C A1 - Wever, P A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Bluetongue KW - Bluetongue virus KW - Cattle KW - Cattle Diseases KW - Costs and Cost Analysis KW - cross-sectional studies KW - Early Diagnosis KW - France KW - Freedom KW - milk KW - Netherlands KW - reproduction KW - Sentinel Surveillance KW - Serogroup AB -

Quick detection and recovery of country's freedom status remain a constant challenge in animal health surveillance. The efficacy and cost efficiency of different surveillance components in proving the absence of infection or (early) detection of bluetongue serotype 8 in cattle populations within different countries (the Netherlands, France, Belgium) using surveillance data from years 2006 and 2007 were investigated using an adapted scenario tree model approach. First, surveillance components (sentinel, yearly cross-sectional and passive clinical reporting) within each country were evaluated in terms of efficacy for substantiating freedom of infection. Yearly cross-sectional survey and passive clinical reporting performed well within each country with sensitivity of detection values ranging around 0.99. The sentinel component had a sensitivity of detection around 0.7. Secondly, how effective the components were for (early) detection of bluetongue serotype 8 and whether syndromic surveillance on reproductive performance, milk production and mortality data available from the Netherlands and Belgium could be of added value were evaluated. Epidemic curves were used to estimate the timeliness of detection. Sensitivity analysis revealed that expected within-herd prevalence and number of herds processed were the most influential parameters for proving freedom and early detection. Looking at the assumed direct costs, although total costs were low for sentinel and passive clinical surveillance components, passive clinical surveillance together with syndromic surveillance (based on reproductive performance data) turned out most cost-efficient for the detection of bluetongue serotype 8. To conclude, for emerging or re-emerging vectorborne disease that behaves such as bluetongue serotype 8, it is recommended to use passive clinical and syndromic surveillance as early detection systems for maximum cost efficiency and sensitivity. Once an infection is detected and eradicated, cross-sectional screening for substantiating freedom of infection and sentinel for monitoring the disease evolution are recommended.

VL - 64 CP - 6 U1 - https://www.ncbi.nlm.nih.gov/pubmed/27670151?dopt=Abstract M3 - 10.1111/tbed.12564 ER - TY - JOUR T1 - Evaluation of 16 commercial antibody ELISAs for the detection of bovine viral diarrhea virus-specific antibodies in serum and milk using well-characterized sample panels. JF - J Vet Diagn Invest Y1 - 2017 A1 - Jean-Baptiste Hanon A1 - Miet De Baere A1 - De la Ferté, Camille A1 - Sophie Roelandt A1 - Yves Van der Stede A1 - Ann Brigitte Cay AB -

We performed a thorough fit-for-purpose evaluation of commercial ELISAs for the detection of bovine viral diarrhea virus (BVDV)-specific antibodies in serum and in milk by testing 2 panels of well-characterized serum and milk samples. Sixteen ELISAs from 9 different manufacturers, available on the Belgian market at the time of our study, were assessed for their diagnostic and analytical sensitivity (DSe and ASe, respectively), diagnostic specificity (DSp), and repeatability relative to the virus neutralization (VN) test considered to be the gold standard assay. Using serum as a matrix, DSe was much lower for competitive (c)ELISAs (min. 45%, max. 65%) than for indirect (i)ELISAs (min. 85%, max. 100%), partly because of the lower detection of positive samples from vaccinated animals included in the panel. ASe was also better for iELISAs; DSp was >95% for all but 2 ELISAs. Repeatability, expressed as coefficients of variation (CV) of optical densities, was generally good, although 3 ELISAs had a mean CV >10%. With milk samples, as observed for serum, DSe was lower for cELISAs (min. 57%, max. 75%) than for iELISAs (min. 61%, max. 89%), and DSp was high for all ELISAs (min. 94%, max. 100%). Both DSe and ASe were lower when testing milk samples compared to serum samples. These results confirm that serologic monitoring of BVDV-free herds should be performed using serum samples of unvaccinated animals to avoid interference of vaccination and to maximize the chance of detecting seroconversion linked to BVDV infection. Further investigations using a larger collection of field samples are recommended.

U1 - http://www.ncbi.nlm.nih.gov/pubmed/28803517?dopt=Abstract M3 - 10.1177/1040638717724839 ER - TY - JOUR T1 - Genetically stable infectious Schmallenberg virus persists in foetal envelopes of pregnant ewes. JF - J Gen Virol Y1 - 2017 A1 - Poskin, Antoine A1 - Martinelle, Ludovic A1 - Yves Van der Stede A1 - Saegerman, Claude A1 - Ann Brigitte Cay A1 - Nick De Regge KW - Animals KW - Antibodies, Viral KW - Base Sequence KW - Bunyaviridae Infections KW - Chorion KW - Female KW - Orthobunyavirus KW - Placenta KW - Pregnancy KW - RNA, Viral KW - Sequence Analysis, RNA KW - Sheep KW - Sheep Diseases AB -

Schmallenberg virus (SBV) is a recently emerged vector-borne virus, inducing congenital defects in bovines, ovines and caprines. Here we have shown that infectious SBV is capable of persisting until the moment of birth in the foetal envelopes of ewes infected with SBV-infectious serum at day 45 (1/5 positive) and 60 (4/6 positive) of gestation. This persistence of at least 100 days is a new aspect of the SBV pathogenesis that could help to explain how SBV overwinters the cold season in temperate climate zones. Furthermore, sequencing of the M segment shows that the persisting virus in the foetal envelopes is genetically stable since only a few mutations compared to the inoculum were found. This supports the hypothesis that persisting virus could start the infection of new hosts. Finally, neutralization tests showed that infectious SBV present in the foetal envelopes at birth can be neutralized by the humoral immunity present in the infected ewes.

VL - 98 CP - 7 U1 - https://www.ncbi.nlm.nih.gov/pubmed/28699878?dopt=Abstract M3 - 10.1099/jgv.0.000841 ER - TY - JOUR T1 - Schmallenberg Virus in Belgium: Estimation of Impact in Cattle and Sheep Herds. JF - Transbound Emerg Dis Y1 - 2017 A1 - Poskin, A A1 - Estelle Méroc A1 - Isabelle Behaeghel A1 - Riocreux, F A1 - Couche, M A1 - Van Loo, H A1 - Bertels, G A1 - Delooz, L A1 - Quinet, C A1 - Marc Dispas A1 - Yves Van der Stede KW - Abortion, Veterinary KW - Animals KW - Belgium KW - Bunyaviridae Infections KW - Cattle KW - Cattle Diseases KW - Disease Outbreaks KW - Orthobunyavirus KW - Sheep KW - Sheep Diseases KW - Stillbirth AB -

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.

VL - 64 CP - 1 U1 - http://www.ncbi.nlm.nih.gov/pubmed/26302467?dopt=Abstract M3 - 10.1111/tbed.12367 ER - TY - JOUR T1 - Application of syndromic surveillance on routinely collected cattle reproduction and milk production data for the early detection of outbreaks of Bluetongue and Schmallenberg viruses. JF - Prev Vet Med Y1 - 2016 A1 - Veldhuis, Anouk A1 - Brouwer-Middelesch, Henriëtte A1 - Marceau, Alexis A1 - Madouasse, Aurélien A1 - Yves Van der Stede A1 - Fourichon, Christine A1 - Sarah Welby A1 - Wever, Paul A1 - van Schaik, Gerdien KW - Animals KW - Belgium KW - Bluetongue KW - Bluetongue virus KW - Bunyaviridae Infections KW - Cattle KW - Cattle Diseases KW - Disease Outbreaks KW - Epidemiological Monitoring KW - Female KW - milk KW - Netherlands KW - Orthobunyavirus KW - Prospective Studies KW - reproduction AB -

This study aimed to evaluate the use of routinely collected reproductive and milk production data for the early detection of emerging vector-borne diseases in cattle in the Netherlands and the Flanders region of Belgium (i.e., the northern part of Belgium). Prospective space-time cluster analyses on residuals from a model on milk production were carried out to detect clusters of reduced milk yield. A CUSUM algorithm was used to detect temporal aberrations in model residuals of reproductive performance models on two indicators of gestation length. The Bluetongue serotype-8 (BTV-8) epidemics of 2006 and 2007 and the Schmallenberg virus (SBV) epidemic of 2011 were used as case studies to evaluate the sensitivity and timeliness of these methods. The methods investigated in this study did not result in a more timely detection of BTV-8 and SBV in the Netherlands and BTV-8 in Belgium given the surveillance systems in place when these viruses emerged. This could be due to (i) the large geographical units used in the analyses (country, region and province level), and (ii) the high level of sensitivity of the surveillance systems in place when these viruses emerged. Nevertheless, it might be worthwhile to use a syndromic surveillance system based on non-specific animal health data in real-time alongside regular surveillance, to increase the sense of urgency and to provide valuable quantitative information for decision makers in the initial phase of an emerging disease outbreak.

VL - 124 U1 - https://www.ncbi.nlm.nih.gov/pubmed/26732291?dopt=Abstract M3 - 10.1016/j.prevetmed.2015.12.006 ER - TY - JOUR T1 - First TBEV serological screening in Flemish wild boar. JF - Infect Ecol Epidemiol Y1 - 2016 A1 - Sophie Roelandt A1 - Vanessa Suin A1 - Yves Van der Stede A1 - Lamoral, Sophie A1 - Sylvie Marché A1 - Marylène Tignon A1 - Saiz, Juan Carlos A1 - Escribano-Romero, Estela A1 - Casaer, Jim A1 - Bernard Brochier A1 - Steven Van Gucht A1 - S. Roels A1 - Vervaeke, Muriel AB -

In the frame of a Flemish wildlife surveillance in 2013, a serological screening was performed on sera from wild boar (Sus scrofa; n=238) in order to detect tick-borne encephalitis virus (TBEV)-specific antibodies. Neutralising antibodies were titrated with a seroneutralisation test (SNT), using two cut-off titres (1/10-1/15). Seven wild boars were found TBEV-seropositive and showed moderate (>1/15) to high (>1/125) SNT-titres; three individuals had borderline results (1/10-1/15). This study demonstrated the presence of TBEV-specific antibodies in wild boar and highlighted potential TBEV-foci in Flanders. Additional surveillance including direct virus testing is now recommended.

VL - 6 U1 - http://www.ncbi.nlm.nih.gov/pubmed/27087689?dopt=Abstract M3 - 10.3402/iee.v6.31099 ER - TY - JOUR T1 - Reconstruction of the Schmallenberg virus epidemic in Belgium: Complementary use of disease surveillance approaches. JF - Vet Microbiol Y1 - 2016 A1 - Poskin, Antoine A1 - Théron, Léonard A1 - Jean-Baptiste Hanon A1 - Saegerman, Claude A1 - Vervaeke, Muriel A1 - Yves Van der Stede A1 - Ann Brigitte Cay A1 - Nick De Regge KW - Animals KW - Animals, Wild KW - Belgium KW - Bunyaviridae Infections KW - Cattle KW - Cattle Diseases KW - Ceratopogonidae KW - Computer Simulation KW - Orthobunyavirus KW - Population Surveillance KW - Reverse Transcriptase Polymerase Chain Reaction KW - Seroepidemiologic Studies AB -

Schmallenberg virus (SBV) emerged across Europe in 2011 and Belgium was among the first countries affected. In this study, published findings are combined with new data from veterinary surveillance networks and the Belgian reference laboratory for SBV at the Veterinary and Agrochemical Research centre (CODA-CERVA) to reconstruct the epidemic in Belgium. First retrospective cases of SBV were reported by veterinarians that observed decreased milk yield and fever in dairy cattle in May 2011. The number of SBV suspicions subsequently increased in adult cattle in August 2011. That month, first SBV positive pools of Culicoides were detected and extensive virus circulation occurred in Belgium during late summer and autumn 2011. As a consequence, most pregnant ruminants were infected and their fetuses exposed to the virus. This resulted in an outbreak of abortions, still-births and malformed new-borns observed between January and April 2012. The number of cases drastically diminished in 2012-2013, although multiple lines of evidence obtained from cross-sectional serological surveys, analyses on aborted foetuses, sentinel herd surveillance and surveillance of SBV in vectors prove that SBV was still circulating in Belgium at that time. Virus circulation was then probably strongly reduced in 2013-2014, while increasing evidence indicates its recirculation in 2014-2015 in Belgium. Based on the experience gathered with the closely related Akabane virus, recurrent outbreaks of congenital events can be expected for a long period. Vaccination of seronegative animals before the first mating could be used to prevent the deleterious effects of SBV. During this epidemic, different surveillance approaches including syndromic surveillance, sentinel herd surveillance, cross-sectional seroprevalence studies and pathogen surveillance in vectors have proven their utility and should be considered to continue in the future.

VL - 183 U1 - http://www.ncbi.nlm.nih.gov/pubmed/26790935?dopt=Abstract M3 - 10.1016/j.vetmic.2015.11.036 ER - TY - JOUR T1 - Evaluation of a hierarchical ascendant clustering process implemented in a veterinary syndromic surveillance system. JF - Prev Vet Med Y1 - 2015 A1 - Isabelle Behaeghel A1 - Veldhuis, Anouk A1 - Ren, Libo A1 - Estelle Méroc A1 - F. Koenen A1 - Pierre Kerkhofs A1 - Yves Van der Stede A1 - Barnouin, Jacques A1 - Marc Dispas KW - Algorithms KW - Animals KW - Belgium KW - Bluetongue KW - Cattle KW - Cattle Diseases KW - Cluster Analysis KW - Epidemiological Monitoring KW - Goat Diseases KW - Goats KW - Models, Theoretical KW - Sensitivity and Specificity KW - Sheep KW - SOFTWARE AB -

Syndromic surveillance is considered as one of the surveillance components for early warning of health-related events, as it allows detection of aberrations in health indicators before laboratory confirmation. "MoSS-Emergences 2" (MoSS-E2), a tool for veterinary syndromic surveillance, aggregates groups of similar clinical observations by hierarchical ascendant classification (HAC). In the present study, this HAC clustering process was evaluated using a reference set of data that, for the purpose of this evaluation, was a priori divided and defined as Bluetongue (BTV) positive cases (PC) on the one hand and BTV negative cases (NC) on the other hand. By comparing the clustering result of MoSS-E2 with the expected outcome, the sensitivity (the ability to cluster PC together) and specificity (the ability to exclude NC from PC) of the clustering process were determined for this set of data. The stability of the classes obtained with the clustering algorithm was evaluated by comparing the MoSS-E2 generated dendrogram (applying complete linkage) with dendrograms of STATA® software applying average and single linkage methods. To assess the systems' robustness, the parameters of the distance measure were adjusted according to different scenarios and obtained outcomes were compared to the expected outcome based on the a priori known labels. Rand indexes were calculated to measure similarity between clustering outcomes. The clustering algorithm in its default settings successfully segregated the reference BTV cases from the non-BTV cases, resulting in a sensitivity of 100.0% (95% CI: 89.0-100.0) and a specificity of 100.0% (95% CI: 80.0-100.0) for this set of data. The different linkage methods showed similar clustering results indicating stability of the classes (Rand indexes of respectively 0.77 for average and 0.75 for single linkage). The system proved to be robust when changing the parameters as the BTV cases remained together in meaningful clusters (Rand indexes between 0.72 and 1). The configurable MoSS-E2 system demonstrated its suitability to identify meaningful clusters of clinical syndromes.

VL - 120 CP - 2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25890820?dopt=Abstract M3 - 10.1016/j.prevetmed.2015.03.002 ER - TY - JOUR T1 - Follow-up of the Schmallenberg Virus Seroprevalence in Belgian Cattle. JF - Transbound Emerg Dis Y1 - 2015 A1 - Estelle Méroc A1 - Poskin, A A1 - Van Loo, H A1 - Van Driessche, E A1 - Czaplicki, G A1 - Quinet, C A1 - Riocreux, F A1 - Nick De Regge A1 - Ann Brigitte Cay A1 - Thierry van den Berg A1 - Hooyberghs, J A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Bunyaviridae Infections KW - Cattle KW - Cattle Diseases KW - cross-sectional studies KW - Follow-Up Studies KW - Orthobunyavirus KW - Risk Factors KW - Seasons KW - Seroepidemiologic Studies AB -

Schmallenberg virus (SBV), which emerged in Northwestern Europe in 2011, is an arthropod-borne virus affecting primarily ruminants. Based on the results of two cross-sectional studies conducted in the Belgian ruminant population during winter 2011-2012, we concluded that at the end of 2011, almost the whole population had already been infected by SBV. A second cross-sectional serological study was conducted in the Belgian cattle population during winter 2012-2013 to examine the situation after the 2012 transmission period and to analyse the change in immunity after 1 year. A total of 7130 blood samples collected between 1st January and 28 February 2013 in 188 herds were tested for the presence of SBV-specific antibodies. All sampled herds tested positive and within-herd seroprevalence was estimated at 65.66% (95% CI: 62.28-69.04). A statistically significant decrease was observed between the beginning and the end of 2012. On the other hand, age-cohort-specific seroprevalence stayed stable from 1 year to the other. During winter 2012-2013, calves between 6 and 12 months had a seroprevalence of 20.59% (95% CI: 15.34-25.83), which seems to be an indication that SBV was still circulating at least in some parts of Belgium during summer-early autumn 2012. Results showed that the level of immunity against SBV of the animals infected has not decreased and remained high after 1 year and that the spread of the virus has slowed down considerably during 2012. This study also indicated that in the coming years, there are likely to be age cohorts of unprotected animals.

VL - 62 CP - 5 U1 - http://www.ncbi.nlm.nih.gov/pubmed/24330658?dopt=Abstract M3 - 10.1111/tbed.12202 ER - TY - JOUR T1 - Persistence of the protective immunity and kinetics of the isotype specific antibody response against the viral nucleocapsid protein after experimental Schmallenberg virus infection of sheep. JF - Vet Res Y1 - 2015 A1 - Poskin, Antoine A1 - Verite, Stephanie A1 - Comtet, Loïc A1 - Yves Van der Stede A1 - Ann Brigitte Cay A1 - Nick De Regge KW - Animals KW - Antibodies, Neutralizing KW - Antibodies, Viral KW - Bunyaviridae Infections KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Immunity, Innate KW - Neutralization Tests KW - Nucleocapsid Proteins KW - Orthobunyavirus KW - Real-Time Polymerase Chain Reaction KW - RNA, Viral KW - Sheep KW - Sheep Diseases AB -

Schmallenberg virus (SBV) is an Orthobunyavirus that induces abortion, stillbirths and congenital malformations in ruminants. SBV infection induces a long lasting seroconversion under natural conditions. The persistence of the protective immunity and the isotype specific antibody response upon SBV infection of sheep has however not been studied in detail. Five sheep were kept in BSL3 facilities for more than 16 months and subjected to repeated SBV infections. Blood was regularly sampled and organs were collected at euthanasia. The presence of SBV RNA in serum and organs was measured with quantitative real-time PCR. The appearance and persistence of neutralizing and SBV nucleoprotein (N) isotype specific antibodies was determined with virus neutralization tests (VNT) and ELISAs. The primo SBV infection protected ewes against clinical signs, viraemia and virus replication in organs upon challenge infections more than 15 months later. Production of neutralizing SBV specific antibodies was first detected around 6 days post primo-inoculation with VNT and correlated with the appearance of SBV-N specific IgM antibodies. These IgM antibodies remained present for 2 weeks. SBV-N specific IgG antibodies were first detected between 10 and 21 dpi and reached a plateau at 28 dpi. This plateau remained consistently high and no significant decrease in titre was found over a period of more than 1 year. Similar results were found for the neutralising antibody response. In conclusion, the SBV specific IgM response probably eliminates SBV from the blood and the protective immunity induced by SBV infection protects sheep against reinfection for at least 16 months.

VL - 46 U1 - http://www.ncbi.nlm.nih.gov/pubmed/26472116?dopt=Abstract M3 - 10.1186/s13567-015-0260-6 ER - TY - JOUR T1 - Serological diagnosis of bovine neosporosis: a Bayesian evaluation of two antibody ELISA tests for in vivo diagnosis in purchased and abortion cattle. JF - Vet Rec Y1 - 2015 A1 - Sophie Roelandt A1 - Yves Van der Stede A1 - Czaplicki, G A1 - Van Loo, H A1 - Van Driessche, E A1 - Dewulf, J A1 - Hooyberghs, J A1 - Faes, C KW - Abortion, Veterinary KW - Animals KW - Antibodies, Protozoan KW - Bayes Theorem KW - Belgium KW - Cattle KW - Cattle Diseases KW - Coccidiosis KW - Commerce KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Neospora KW - Pregnancy KW - Seroepidemiologic Studies AB -

Currently, there are no perfect reference tests for the in vivo detection of Neospora caninum infection. Two commercial N caninum ELISA tests are currently used in Belgium for bovine sera (TEST A and TEST B). The goal of this study is to evaluate these tests used at their current cut-offs, with a no gold standard approach, for the test purpose of (1) demonstration of freedom of infection at purchase and (2) diagnosis in aborting cattle. Sera of two study populations, Abortion population (n=196) and Purchase population (n=514), were selected and tested with both ELISA's. Test results were entered in a Bayesian model with informative priors on population prevalences only (Scenario 1). As sensitivity analysis, two more models were used: one with informative priors on test diagnostic accuracy (Scenario 2) and one with all priors uninformative (Scenario 3). The accuracy parameters were estimated from the first model: diagnostic sensitivity (Test A: 93.54 per cent-Test B: 86.99 per cent) and specificity (Test A: 90.22 per cent-Test B: 90.15 per cent) were high and comparable (Bayesian P values >0.05). Based on predictive values in the two study populations, both tests were fit for purpose, despite an expected false negative fraction of ±0.5 per cent in the Purchase population and ±5 per cent in the Abortion population. In addition, a false positive fraction of ±3 per cent in the overall Purchase population and ±4 per cent in the overall Abortion population was found.

VL - 176 CP - 23 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25861822?dopt=Abstract M3 - 10.1136/vr.102872 ER - TY - JOUR T1 - A trend analysis of antimicrobial resistance in commensal Escherichia coli from several livestock species in Belgium (2011-2014). JF - Prev Vet Med Y1 - 2015 A1 - Jean-Baptiste Hanon A1 - Jaspers, Stijn A1 - Butaye, Patrick A1 - P Wattiau A1 - Estelle Méroc A1 - Aerts, Marc A1 - Hein Imberechts A1 - Vermeersch, Katie A1 - Yves Van der Stede KW - Animals KW - Anti-Bacterial Agents KW - Belgium KW - Cattle KW - Cattle Diseases KW - Chickens KW - Drug Resistance, Multiple, Bacterial KW - Escherichia coli KW - Escherichia coli Infections KW - Feces KW - Microbial Sensitivity Tests KW - Poultry Diseases KW - prevalence KW - Seasons KW - Swine KW - Swine Diseases AB -

A temporal trend analysis was performed on antimicrobial resistance data collected over 4 consecutive years (2011-2014) in the official Belgian antimicrobial resistance monitoring programme. Commensal Escherichia coli strains were isolated from faecal samples of four livestock categories (veal calves, young beef cattle, broiler chickens and slaughter pigs) and the trends of resistance profiles were analysed. The resistance prevalence remained high (>50%) during the study period for ampicillin in veal calves and chickens, for ciprofloxacin and nalidixic acid in chickens, for sulfamethoxazole in veal calves, chickens and pigs and for tetracycline in veal calves. Using logistic regression and Generalized Estimating Equation and after p value adjustment for multiple testing (Linear step-up method), statistically significant decreasing temporal trends were observed for several of the 11 tested antimicrobials in several livestock categories: in veal calves (10/11), in chickens (6/11) and in pigs (5/11). A significant increasing trend was observed for the prevalence of resistance to ciprofloxacin in chickens. Multi-resistance, considered as the resistance to at least three antimicrobials of different antibiotic classes, was observed in the four livestock categories but was significantly decreasing in veal calves, chickens and pigs. Overall, the prevalence of resistance and of multi-resistance was lowest in the beef cattle livestock category and highest in broiler chickens. These decreasing temporal trends of antimicrobial resistance might be due to a decrease of the total antimicrobial consumption for veterinary use in Belgium which was reported for the period between 2010 and 2013. The methodology and statistical tools developed in this study provide outputs which can detect shifts in resistance levels or resistance trends associated with particular antimicrobial classes and livestock categories. Such outputs can be used as objective evidence to evaluate the possible efficacy of measures taken by animal health authorities and stakeholders in the livestock sector to limit antimicrobial resistance occurrence.

VL - 122 CP - 4 U1 - http://www.ncbi.nlm.nih.gov/pubmed/26423778?dopt=Abstract M3 - 10.1016/j.prevetmed.2015.09.001 ER - TY - JOUR T1 - Autochthonous tick-borne encephalitis virus-seropositive cattle in Belgium: a risk-based targeted serological survey. JF - Vector Borne Zoonotic Dis Y1 - 2014 A1 - Sophie Roelandt A1 - Vanessa Suin A1 - Riocreux, Flavien A1 - Lamoral, Sophie A1 - Van der Heyden, Sara A1 - Yves Van der Stede A1 - Bénédicte Lambrecht A1 - Ann Brigitte Cay A1 - Bernard Brochier A1 - S. Roels A1 - Steven Van Gucht KW - Animals KW - Antibodies, Viral KW - Arachnid Vectors KW - Belgium KW - Cattle KW - Cattle Diseases KW - cross-sectional studies KW - Encephalitis Viruses, Tick-Borne KW - Encephalitis, Tick-Borne KW - Female KW - Humans KW - Ixodes KW - mice KW - risk KW - Sentinel Surveillance KW - Seroepidemiologic Studies KW - Zoonoses AB -

The risk of tick-borne encephalitis virus (TBEV) introduction into Belgium remains high, and the presence of infected wildlife in Belgium is suspected. Domestic animals can serve as excellent sentinels for TBEV surveillance to install an early warning surveillance component for this emerging zoonotic disease of public health importance. In a targeted, risk-based and cross-sectional sampling design, serological screening was performed on Belgian cattle (n=650), selected from the 2010 Belgian national cattle surveillance serum bank. All samples were subjected to a gold standard TBEV seroneutralization test (SNT), based on the rapid fluorescent focus inhibition test (RFFIT) protocol. Seventeen bovines were seropositive (titer >1/15) and six had borderline results (1/10 < titer < 1/15). The accuracy of the RFFIT-SNT was confirmed in a mouse inoculation test. The overall bovine TBEV seroprevalence in the targeted area was estimated between 2.61% and 4.29%. This confirms for the first time the presence of infected foci in Belgium. Further surveillance in cattle, other sentinels, ticks, and humans at risk is recommended to further determine the location and size of endemic foci and the risk for public health.

VL - 14 CP - 9 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25229702?dopt=Abstract M3 - 10.1089/vbz.2014.1576 ER - TY - JOUR T1 - Detection of total and PRRSV-specific antibodies in oral fluids collected with different rope types from PRRSV-vaccinated and experimentally infected pigs. JF - BMC Vet Res Y1 - 2014 A1 - Decorte, Inge A1 - Van Breedam, Wander A1 - Yves Van der Stede A1 - Nauwynck, Hans J A1 - Nick De Regge A1 - Ann Brigitte Cay KW - Animals KW - Antibodies, Viral KW - cannabis KW - Cotton Fiber KW - Female KW - Immunoglobulin Isotypes KW - Nylons KW - Polyesters KW - Porcine Reproductive and Respiratory Syndrome KW - Porcine respiratory and reproductive syndrome virus KW - Saliva KW - specimen handling KW - Swine KW - Viral Vaccines AB -

BACKGROUND: Oral fluid collected by means of ropes has the potential to replace serum for monitoring and surveillance of important swine pathogens. Until now, the most commonly used method to collect oral fluid is by hanging a cotton rope in a pen. However, concerns about the influence of rope material on subsequent immunological assays have been raised. In this study, we evaluated six different rope materials for the collection of oral fluid and the subsequent detection of total and PRRSV-specific antibodies of different isotypes in oral fluid collected from PRRSV-vaccinated and infected pigs.

RESULTS: An initial experiment showed that IgA is the predominant antibody isotype in porcine saliva. Moreover, it was found that synthetic ropes may yield higher amounts of IgA, whereas all rope types seemed to be equally suitable for IgG collection. Although IgA is the predominant antibody isotype in porcine oral fluid, the PRRSV-specific IgA-based IPMA and ELISA tests were clearly not ideal for sensitive detection of PRRSV-specific IgA antibodies. In contrast, PRRSV-specific IgG in oral fluids was readily detected in PRRSV-specific IgG-based IPMA and ELISA tests, indicating that IgG is a more reliable isotype for monitoring PRRSV-specific antibody immunity in vaccinated/infected animals via oral fluids with the currently available tests.

CONCLUSIONS: Since PRRSV-specific IgG detection seems more reliable than PRRSV-specific IgA detection for monitoring PRRSV-specific antibody immunity via oral fluids, and since all rope types yield equal amounts of IgG, it seems that the currently used cotton ropes are an appropriate choice for sample collection in PRRSV monitoring.

VL - 10 U1 - http://www.ncbi.nlm.nih.gov/pubmed/24938323?dopt=Abstract M3 - 10.1186/1746-6148-10-134 ER - TY - JOUR T1 - Distinction between persistent and transient infection in a bovine viral diarrhoea (BVD) control programme: appropriate interpretation of real-time RT-PCR and antigen-ELISA test results. JF - Transbound Emerg Dis Y1 - 2014 A1 - Jean-Baptiste Hanon A1 - Yves Van der Stede A1 - Antonissen, A A1 - Mullender, C A1 - Marylène Tignon A1 - Thierry van den Berg A1 - Ann Brigitte Cay KW - Animals KW - Antibodies, Viral KW - Antigens, Viral KW - Belgium KW - Bovine Virus Diarrhea-Mucosal Disease KW - Cattle KW - Diarrhea Virus 1, Bovine Viral KW - Diarrhea Viruses, Bovine Viral KW - Enzyme-Linked Immunosorbent Assay KW - Follow-Up Studies KW - Real-Time Polymerase Chain Reaction KW - Retrospective Studies KW - RNA, Viral AB -

Control of bovine viral diarrhoea (BVD) in Belgium is currently implemented on a voluntary basis at herd level and mainly relies on detection and culling of persistently infected (PI) animals. The present field study was conducted during the winter of 2010/2011 to assess the performances of diagnostic assays used in the testing scheme for BVD as proposed by the two Belgian regional laboratories. Individual blood samples were collected from 4972 animals, and individual samples from the same herd were pooled (maximum of 30 individual samples per pool) and screened for the presence of Bovine Viral Diarrhoea Virus (BVDV)-specific RNA using a commercial real-time RT-PCR test (ADIAGENE). Individual samples from positive pools were then tested in parallel with the same RT-PCR test and with an antigen-capture ELISA test (IDEXX) to detect viremic animals. This study demonstrated that individual results differed according to the type of assay used (P < 0.001): 140 animals (2.8%) were positive by RT-PCR and 72 (1.4%) by antigen-ELISA. A second blood sample was taken 40 days later from 74 PCR positive animals to detect persistent viremia: 17 (23%) of these were still PCR positive and considered to be PI and the 57 that no longer tested positive were assumed to be transiently infected (TI) animals. All PI animals were positive also by antigen-ELISA at both time points. Among TI animals, 10 (16%) were positive by antigen-ELISA at the first but none at the second sampling. A highly significant difference in cycle threshold (Ct ) values obtained by RT-PCR was observed between PI and TI animals. ROC analysis was performed to establish thresholds to confirm with high probability that an animal is PI, based on the result of RT-PCR test performed on a single individual blood sample.

VL - 61 CP - 2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23009318?dopt=Abstract M3 - 10.1111/tbed.12011 ER - TY - JOUR T1 - Distribution of Schmallenberg virus and seroprevalence in Belgian sheep and goats. JF - Transbound Emerg Dis Y1 - 2014 A1 - Estelle Méroc A1 - Nick De Regge A1 - Riocreux, F A1 - Ann Brigitte Cay A1 - Thierry van den Berg A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Bunyaviridae Infections KW - Epidemics KW - Goat Diseases KW - Goats KW - Orthobunyavirus KW - Seroepidemiologic Studies KW - Sheep KW - Sheep Diseases AB -

A serological survey to detect Schmallenberg virus (SBV)-specific antibodies by ELISA was organized in the Belgian sheep population to study the seroprevalence at the end of the epidemic. One thousand eighty-two sheep samples which were collected from 83 herds all over Belgium between November 2011 and April 2012 were tested. The overall within-herd seroprevalence and the intraclass correlation coefficient were estimated at 84.31% (95% CI: 84.19-84.43) and 0.34, respectively. The overall between-herd seroprevalence was 98.03% (95% CI: 97.86-98.18). A spatial cluster analysis identified a cluster of six farms with significantly lower within-herd seroprevalence in the south of Belgium compared with the rest of the population (P = 0.04). It was shown that seroprevalence was associated to flock density and that the latter explained the presence of the spatial cluster. Additionally, 142 goat samples from eight different herds were tested for SBV-specific antibodies. The within-herd seroprevalence in goats was estimated at 40.68% (95% CI: 23.57-60.4%). The results of the current study provided evidence that almost every Belgian sheep herd has been in contact with SBV during 2011 and should be taken into consideration as part of comprehensive SBV surveillance and control strategies.

VL - 61 CP - 5 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23305427?dopt=Abstract M3 - 10.1111/tbed.12050 ER - TY - Generic T1 - Evaluation de la surveillance épidémiologique belge en santé animale. Y1 - 2014 A1 - S. Cardoen A1 - Depoorter,P. A1 - Hendrikx,P. A1 - Hooyberghs,J. A1 - Hein Imberechts A1 - Dewulf,J. A1 - G. Czaplicki A1 - Yves Van der Stede A1 - Katelijne Dierick A1 - Thierry van den Berg A1 - Stoop,S. A1 - Hubaux,M. A1 - Sophie Quoilin A1 - Saegerman,C. ED - FAVV-AFSCA KW - Belge KW - de KW - EN KW - EVALUATION KW - santé KW - Surveillance KW - surveillance,maladies animales,organisation,recommandations JF - Evaluation de la surveillance épidémiologique belge en santé animale. VL - 66 CP - AFSCA U1 - 39149 U2 - 19/03/2014 ER - TY - JOUR T1 - Exploring cattle movements in Belgium. JF - Prev Vet Med Y1 - 2014 A1 - Ensoy, Chellafe A1 - Faes, Christel A1 - Sarah Welby A1 - Yves Van der Stede A1 - Aerts, Marc KW - Animal Husbandry KW - Animals KW - Belgium KW - Bluetongue KW - Bluetongue virus KW - Cattle KW - Cattle Diseases KW - Risk Assessment KW - Seasons KW - Spatial Analysis KW - Transportation AB -

Movement of animals from one farm to another is a potential risk and can lead to the spreading of livestock diseases. Therefore, in order to implement effective control measures, it is important to understand the movement network in a given area. Using the SANITEL data from 2005 to 2009, around 2 million cattle movements in Belgium were traced. Exploratory analysis revealed different spatial structures for the movement of different cattle types: fattening calves are mostly moved to the Antwerp region, adult cattle are moved to different parts in Belgium. Based on these differences, movement of cattle would more likely cause a spread of disease to a larger number of areas in Belgium as compared to the fattening calves. A closer inspection of the spatial and temporal patterns of cattle movement using a weighted negative binomial model, revealed a significant short-distance movement of bovine which could be an important factor contributing to the local spreading of a disease. The model however revealed hot spot areas of movement in Belgium; four areas in the Walloon region (Luxembourg, Hainaut, Namur and Liege) were found as hot spot areas while East and West Flanders are important "receivers" of movement. This implies that an introduction of a disease to these Walloon regions could result in a spread toward the East and West Flanders regions, as what happened in the case of Bluetongue BTV-8 outbreak in 2006. The temporal component in the model also revealed a linear trend and short- and long-term seasonality in the cattle movement with a peak around spring and autumn. The result of this explorative analysis enabled the identification of "hot spots" in time and space which is important in enhancing any existing monitoring and surveillance system.

VL - 116 CP - 1-2 U1 - https://www.ncbi.nlm.nih.gov/pubmed/24881483?dopt=Abstract M3 - 10.1016/j.prevetmed.2014.05.003 ER - TY - JOUR T1 - Bluetongue surveillance system in Belgium: a stochastic evaluation of its risk-based approach effectiveness. JF - Prev Vet Med Y1 - 2013 A1 - Sarah Welby A1 - Estelle Méroc A1 - Faes, Christel A1 - Kris De Clercq A1 - Hooyberghs, Jozef A1 - Mintiens, Koen A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Bluetongue KW - Bluetongue virus KW - Cattle KW - Cattle Diseases KW - Disease Outbreaks KW - Enzyme-Linked Immunosorbent Assay KW - Models, Theoretical KW - polymerase chain reaction KW - Population Surveillance KW - Risk Assessment KW - Seasons KW - Sensitivity and Specificity KW - Sentinel Surveillance KW - Sheep KW - Stochastic Processes AB -

BACKGROUND: The aim of this study was to assess the sensitivity of the four major bluetongue surveillance components implemented in Belgium in 2007 for farmed animals and prescribed by the European Union regulation; winter serological screening, sentinel system, passive clinical surveillance, export testing. Scenario tree methodology was used to evaluate the relative sensitivity of detection and targeted approach of each component in terms of early detection and freedom of infection substantiation. Field data collected from the previous year's outbreaks in Belgium were used to determine the risk groups to be considered.

RESULTS: The best sensitivities at herd level, taking into account the diagnostic test sensitivity, design prevalence and the number of animals tested within a herd were obtained with the winter screening and sentinel component. The sensitivities at risk group level, taking into account the obtained herd sensitivity, effective probabilities of infection and number of herds tested were high in all components, except for the export component. Component sensitivities ranged between 0.77 and 1 for all components except for the export component with a mean value of 0.22 (0.17-0.26). In terms of early detection, the probability of detection was best using the passive clinical component or the sentinel component. Sensitivity analysis showed that the passive clinical component sensitivity was mostly affected by the diagnostic process and the number of herds sampled. The sentinel and export components sensitivity were mainly affected by the relative risk estimates whereas the winter screening component was mainly affected by the assumptions about the design prevalence.

CONCLUSIONS: This study revealed interesting features regarding the sensitivity of detection and early detection of infection in the different surveillance components and their risk based approach as requested by the international standards.

VL - 112 CP - 1-2 U1 - https://www.ncbi.nlm.nih.gov/pubmed/23938251?dopt=Abstract M3 - 10.1016/j.prevetmed.2013.07.005 ER - TY - JOUR T1 - Effect of a DIVA vaccine with and without in-feed use of coated calcium-butyrate on transmission of Salmonella Typhimurium in pigs. JF - BMC Vet Res Y1 - 2013 A1 - De Ridder, Lotte A1 - Maes, Dominiek A1 - Dewulf, Jeroen A1 - Pasmans, Frank A1 - Boyen, Filip A1 - Haesebrouck, Freddy A1 - Estelle Méroc A1 - S. Roels A1 - Leyman, Bregje A1 - Butaye, Patrick A1 - Yves Van der Stede KW - Animals KW - Animals, Newborn KW - Butyrates KW - Calcium KW - Dietary Supplements KW - Enzyme-Linked Immunosorbent Assay KW - Feces KW - Salmonella Infections, Animal KW - Salmonella typhimurium KW - Salmonella Vaccines KW - Swine KW - Swine Diseases AB -

BACKGROUND: For satisfactory Salmonella control, good biosecurity along the pork production chain is crucial, although additional control measures on-farm need to be considered. This study evaluated the effect of two potential control measures against the spread of Salmonella Typhimurium via a transmission experiment with 56 piglets (3-15 weeks of age): two groups were orally vaccinated with 107 - 108 Colony Forming Units (CFU)/2 mL of a new attenuated Salmonella Typhimurium vaccine 'Salmoporc-∆rfaJ' with DIVA capacities (Differentiation between Infected and Vaccinated Animals) (n = 2x16); the feed of one group was additionally supplemented with coated calcium-butyrate salt. Two weeks post vaccination, four pigs per group were orally challenged with 107 CFU/2 mL of a Salmonella Typhimurium strain 112910a. Both groups were compared with a positive (challenged/untreated; n = 16) and negative (unchallenged/untreated; n = 8) control group. Until six weeks post challenge, blood, individual faecal and finally tissue samples were examined. Adjusted transmission ratios 'Ra' were estimated, based on the challenge strain isolation from faecal and/or tissue samples.

RESULTS: In both intervention groups, Ra values were lower compared to the positive control group, although these differences were not significant. In the combination group DIVA vaccine + coated butyrate, less non-challenged contact animals excreted Salmonella and less tissue samples were found Salmonella-positive in all pigs, when compared to the positive control group (P < 0.01). Seroconversion was detected in none of the vaccinated animals before challenge, when using a commercial lipopolysaccharide (LPS) ELISA targeting only Salmonella O-antigens, deleted in this vaccine. This was in contrast with an in-house whole-cell ELISA testing for various Salmonella antigens, in which Salmonella-specific antibodies were found pre-challenge in the serum of the vaccinated pigs.

CONCLUSIONS: Both interventions showed a limited, non-significant reduction of Salmonella transmission between piglets. They may have applications towards Salmonella control and surveillance. Firstly, the number of Salmonella excreting contact pigs was significantly lower in the group where vaccination was combined with coated calcium-butyrate salt in the feed; secondly, the new vaccine confirmed its DIVA capacity. Therefore, these interventions merit further research with larger sample sizes, to optimize their use for Salmonella programmes.

VL - 9 U1 - http://www.ncbi.nlm.nih.gov/pubmed/24304918?dopt=Abstract M3 - 10.1186/1746-6148-9-243 ER - TY - JOUR T1 - Effect of saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus in oral fluid by quantitative reverse transcriptase real-time PCR. JF - Vet J Y1 - 2013 A1 - Decorte, Inge A1 - Yves Van der Stede A1 - Nauwynck, Hans A1 - Nick De Regge A1 - Ann Brigitte Cay KW - Animals KW - Excipients KW - Porcine respiratory and reproductive syndrome virus KW - Real-Time Polymerase Chain Reaction KW - Reverse Transcriptase Polymerase Chain Reaction KW - RNA, Viral KW - Saliva KW - specimen handling KW - Swine AB -

This study evaluated the effect of extraction-amplification methods, storage temperature and saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus (PRRSV) RNA by quantitative reverse transcriptase real-time PCR (qRT-PCR) in porcine oral fluid. The diagnostic performance of different extraction-amplification methods was examined using a dilution series of oral fluid spiked with PRRSV. To determine RNA stability, porcine oral fluid, with or without commercially available saliva stabilisers, was spiked with PRRSV, stored at 4°C or room temperature and tested for the presence of PRRSV RNA by qRT-PCR. PRRSV RNA could be detected in oral fluid using all extraction-amplification combinations, but the limit of detection varied amongst different combinations. Storage temperature and saliva stabilisers had an effect on the stability of PRRSV RNA, which could only be detected for 7 days when PRRSV spiked oral fluid was kept at 4°C or stabilised at room temperature with a commercial mRNA stabiliser.

VL - 197 CP - 2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23489844?dopt=Abstract M3 - 10.1016/j.tvjl.2013.02.001 ER - TY - JOUR T1 - Large-scale cross-sectional serological survey of Schmallenberg virus in Belgian cattle at the end of the first vector season. JF - Transbound Emerg Dis Y1 - 2013 A1 - Estelle Méroc A1 - Poskin, A A1 - Van Loo, H A1 - Quinet, C A1 - Van Driessche, E A1 - Delooz, L A1 - Isabelle Behaeghel A1 - Riocreux, F A1 - Hooyberghs, J A1 - Nick De Regge A1 - Ann Brigitte Cay A1 - Thierry van den Berg A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Bunyaviridae Infections KW - Cattle KW - Cattle Diseases KW - cross-sectional studies KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Orthobunyavirus KW - Seasons KW - Seroepidemiologic Studies KW - Serologic Tests AB -

A cross-sectional survey was conducted in the Belgian cattle population after the first period of infection of the emerging Schmallenberg virus. A total number of 11 635 cattle from 422 herds sampled between 2 January and 7 March 2012 were tested for the presence of Schmallenberg-specific antibodies using an ELISA kit. Between-herd seroprevalence in cattle was estimated at 99.76% (95% CI: 98.34-99.97) and within-herd seroprevalence at 86.3% (95% CI: 84.75-87.71). An Intraclass Correlation Coefficient of 0.3 (P < 0.001) was found, indicating that the correlation between two animals within a herd with respect to their serological status was high. Those results corroborate the conclusion that the Schmallenberg virus was widespread in Belgium during winter 2011. Seroprevalence was shown to be statistically associated to the animal's age (P < 0.0001): with 64.9% (95% CI: 61.34-68.3) estimated for the 6-12 months of age, 86.79% (95% CI: 84.43-88.85) for the 12-24 months of age and 94.4% (95% CI: 93.14-95.44) for the animals older than 24 months. Based on the results of the described serological survey, we can conclude that after the first Schmallenberg virus episode, almost every Belgian cattle has already been in contact with the virus. In consequence, the vast majority of the host animals should have developed post infection protective immunity against the virus.

VL - 60 CP - 1 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23206240?dopt=Abstract M3 - 10.1111/tbed.12042 ER - TY - JOUR T1 - Serological and virological BVDV prevalence and risk factor analysis for herds to be BVDV seropositive in Belgian cattle herds. JF - Prev Vet Med Y1 - 2013 A1 - Sarrazin, Steven A1 - Veldhuis, Anouk A1 - Estelle Méroc A1 - Vangeel, Ilse A1 - Laureyns, Jozef A1 - Dewulf, Jeroen A1 - Ann Brigitte Cay A1 - Piepers, Sofie A1 - Hooyberghs, Jozef A1 - Ribbens, Stefaan A1 - Yves Van der Stede KW - Animals KW - Antibodies, Viral KW - Antigens, Viral KW - Belgium KW - Bovine Virus Diarrhea-Mucosal Disease KW - Cattle KW - cross-sectional studies KW - Diarrhea Viruses, Bovine Viral KW - Enzyme-Linked Immunosorbent Assay KW - Logistic Models KW - prevalence KW - Risk Factors KW - Seroepidemiologic Studies KW - Surveys and Questionnaires KW - Vaccination AB -

Bovine viral diarrhoea virus (BVDV) is a worldwide spread virus that most commonly infects cattle and can cause considerable economic losses. To determine the prevalence of BVDV in Belgium, a cross-sectional study was performed between November 2009 and March 2010. Young stock aged between 6 and 12 months from 773 randomly selected Belgian cattle herds were tested for BVDV-specific antibodies and antigen. With a target and maximum of 10 animals per sampled herd, a total of 5246 animals were selected. Additionally a questionnaire including different herd management topics and questions about participation in animal health programmes, including BVDV, was sent to 1100 Belgian cattle herds, including the 773 herds for BVDV testing. This paper focuses on results regarding these 773 herds. The true prevalence of BVDV-specific antibodies and antigen at herd level was respectively 47.4% and 4.4%, while at animal level this was respectively 32.9% and 0.3%. In 44.4% of the herds where BVDV-specific antibodies were detected at least 60% of the sampled young stock was BVDV seropositive. Interestingly, 83.4% of these farmers stated not to have suffered from problems related to BVDV. Moreover, only 8.4% of all farmers who completed the questionnaire (n=895) reported problems possibly related to BVDV the past 3 years. This demonstrates that farmers are often unaware of the presence of BVDV in their herd. Risk factors for a herd to be BVDV seropositive were identified by means of a multivariable logistic regression model. Large herds were significantly more likely to be BVDV seropositive (OR=1.004, p<0.01). The interaction between "Antigen positive animal detected in this study" and "BVDV vaccination in 2009" was significant (p<0.01). In non-vaccinating herds, the detection of antigen positive animals was significantly associated with BVDV seropositive herds (OR=13.8, p<0.01). In herds with no antigen positive animals detected, vaccination resulted in a significant risk factor to be BVDV seropositive compared to non-vaccinating herds (OR=3.4, p<0.01). Herds reporting BVDV-related problems the past 3 years were more likely to be BVDV seropositive (OR=1.9, p<0.05). This relation became non-significant (OR=1.8, p=0.08) when only a subset of herds with no vaccination of animals <12 months was taken into account. The results of the current study suggest an active circulation of BVDV in a considerable number of Belgian cattle herds.

VL - 108 CP - 1 U1 - http://www.ncbi.nlm.nih.gov/pubmed/22878124?dopt=Abstract M3 - 10.1016/j.prevetmed.2012.07.005 ER - TY - Generic T1 - Tick-borne encephalitis virus - seropositive cattle in Belgium: a risk-based screening for (TBEV) antibodies in bovine sera Y1 - 2013 A1 - Sophie Roelandt A1 - Vanessa Suin A1 - Riocreux,F. A1 - S. Lamoral A1 - Yves Van der Stede A1 - Steven Van Gucht A1 - Bernard Brochier A1 - S. Roels ED - Technical University of Denmark KW - a KW - antibodies KW - Antibody KW - association KW - Belgium KW - Cattle KW - conference KW - International KW - SCREENING KW - serum KW - TBEV KW - VIRUS JF - MedVetNet Association International Scientific Conference 2013 CP - Technical University of Denmark U1 - 38336 U2 - 24-25/06/2013 ER - TY - Generic T1 - Tick-borne encephalitis virus (TBEV) - Seroprevalence study for TBEV antibodies in bovine sera in Belgium: a risk-based screening Y1 - 2013 A1 - Vanessa Suin A1 - Sophie Roelandt A1 - S. Lamoral A1 - Riocreux,F. A1 - Yves Van der Stede A1 - Bernard Brochier A1 - S. Roels A1 - Steven Van Gucht KW - a KW - antibodies KW - Antibody KW - Belgium KW - SCREENING KW - serum KW - study KW - TBEV KW - VIRUS JF - Epizone PB - NA CY - NA CP - Epizone U1 - 38361 U2 - October 2013 ER - TY - JOUR T1 - Bovine tuberculosis surveillance alternatives in Belgium. JF - Prev Vet Med Y1 - 2012 A1 - Sarah Welby A1 - Govaerts, M A1 - Vanholme, L A1 - Hooyberghs, J A1 - Mennens, K A1 - Maes, L A1 - Yves Van der Stede KW - Animals KW - Belgium KW - Cattle KW - Decision Trees KW - Disease Outbreaks KW - Epidemiological Monitoring KW - Models, Biological KW - Mycobacterium bovis KW - Population Surveillance KW - Sensitivity and Specificity KW - Stochastic Processes KW - Tuberculosis, Bovine AB -

Belgium obtained the bovine tuberculosis (bTB) officially free status in 2003 (EC Decision 2003/467/EC). This study was carried out to evaluate the components of the current bTB surveillance program in Belgium and to determine the sensitivity of this program. Secondly, alternatives to optimize the bTB surveillance in accordance with European legislation (Council Directive 64/432/EEC) were evaluated. Separate scenario trees were designed for each active surveillance component of the bTB surveillance program. Data from 2005 to 2009 regarding cattle population, movement and surveillance were collected to feed the stochastic scenario tree simulation model. A total of 7,403,826 cattle movement history records were obtained for the 2,678,020 cattle from 36,059 cattle herds still active in 2009. The current surveillance program sensitivity as well as the impact of alternative surveillance protocols was simulated in a stochastic model using 10,000 iterations per simulation. The median (50% percentile) of the component sensitivities across 10,000 iterations was 0.83, 0.85, 0.99, 0.99, respectively, for (i) testing the cattle only during the winter screening, (ii) testing only imported cattle, (iii) testing only purchased cattle and (iv) testing only all slaughtered cattle. The sensitivity analysis showed that the most influential input parameter explaining the variability around the output came from the uncertainty distribution around the sensitivity of the diagnostic tests used within the bTB surveillance. Providing all animals are inspected and post mortem inspection is highly sensitive, slaughterhouse surveillance was the most effective surveillance component. If these conditions were not met, the uncertainty around the mean sensitivity of this component was important. Using an antibody ELISA at purchase and an interferon gamma test during winter screening and at import would increase greatly the sensitivity and the confidence level of Belgium's freedom from bTB infection status.

VL - 106 CP - 2 U1 - https://www.ncbi.nlm.nih.gov/pubmed/22398252?dopt=Abstract M3 - 10.1016/j.prevetmed.2012.02.010 ER - TY - JOUR T1 - Evaluation of four enzyme-linked immunosorbent assays for the serologic survey of avian influenza in wild bird species. JF - Avian Dis Y1 - 2012 A1 - Claes, Gerwin A1 - Vangeluwe, Didier A1 - Yves Van der Stede A1 - Thierry van den Berg A1 - Bénédicte Lambrecht A1 - Sylvie Marché KW - Animals KW - Animals, Wild KW - Birds KW - Enzyme-Linked Immunosorbent Assay KW - Influenza in Birds KW - Seroepidemiologic Studies KW - Serologic Tests AB -

Wild birds that reside in aquatic environments are the major reservoir of avian influenza viruses (AIVs). Since this reservoir of AIVs forms a constant threat for poultry, many countries have engaged in AIV surveillance. More and more commercial enzyme-linked immunosorbent assays (ELISA) are available for serologic surveillance, but these tests are often developed and validated for use in domestic poultry. However, for a correct interpretation of ELISA test results from wild bird sera, more information is needed. In the present study, four ELISA test kits (ID-Vet IDScreen, IDEXX FlockChek AI MultiS-Screen Ab Test Kit, Synbiotics FluDETECTBE, and BioChek AIMSp) were compared for the serologic analysis of 172 serum samples from mallard, mute swan, and Canada goose. Samples were selected based on ID-Vet IDScreen results to obtain an approximately equal number of positive and negative samples. In addition, 92 serum samples from experimentally infected specific-pathogen-free (SPF) chickens and Pekin ducks were included in the tests for validation purposes. Cohen's kappa statistics and Spearman correlation coefficients were calculated for each combination of two tests and for each bird species. Test agreement for mallard sera varied from poor to moderate, while test results for Canada goose and swan sera agreed from fair to almost perfect. The best agreement was obtained with sera from experimentally infected SPF chickens and Pekin ducks. This study shows that some care must be taken before using nucleoprotein ELISAs for the testing of sera from wild birds and that more reliable validation studies should be considered before their use in the serologic surveillance of wild birds.

VL - 56 CP - 4 Suppl U1 - http://www.ncbi.nlm.nih.gov/pubmed/23402117?dopt=Abstract M3 - 10.1637/10165-040912-Reg.1 ER - TY - JOUR T1 - Quantitative characterization of agglomerates and aggregates of pyrogenic and precipitated amorphous silica nanomaterials by transmission electron microscopy. JF - J Nanobiotechnology Y1 - 2012 A1 - Pieter-Jan De Temmerman A1 - Van Doren, Elke A1 - Eveline Verleysen A1 - Yves Van der Stede A1 - Michel Abi Daoud Francisco A1 - Jan Mast KW - Chemical Precipitation KW - Microscopy, Electron, Transmission KW - Nanostructures KW - Particle Size KW - Principal Component Analysis KW - Silicon Dioxide KW - SOFTWARE KW - Sonication KW - Temperature AB -

BACKGROUND: The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM.

RESULTS: Bright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose.Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM.

CONCLUSION: The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor.

VL - 10 U1 - http://www.ncbi.nlm.nih.gov/pubmed/22709926?dopt=Abstract M3 - 10.1186/1477-3155-10-24 ER - TY - JOUR T1 - Comparison of Salmonella enteritidis phage types isolated from layers and humans in Belgium in 2005. JF - Foodborne Pathog Dis Y1 - 2011 A1 - Sarah Welby A1 - Hein Imberechts A1 - Riocreux, Flavien A1 - Sophie Bertrand A1 - Katelijne Dierick A1 - Wildemauwe, Christa A1 - Hooyberghs, Jozef A1 - Yves Van der Stede KW - Animals KW - Bacteriophage Typing KW - Bacteriophages KW - Belgium KW - Chickens KW - Female KW - Humans KW - Poultry Diseases KW - Salmonella enteritidis KW - Salmonella Infections KW - Salmonella Infections, Animal KW - Seasons AB -

OBJECTIVES: The aim of this study was to investigate the available results for Belgium of the European Union coordinated monitoring program (2004/665 EC) on Salmonella in layers in 2005, as well as the results of the monthly outbreak reports of Salmonella Enteritidis in humans in 2005 to identify a possible statistical significant trend in both populations.

MATERIALS AND METHODS: Separate descriptive statistics and univariate analysis were carried out and the parametric and/or non-parametric hypothesis tests were conducted. A time cluster analysis was performed for all Salmonella Enteritidis phage types (PTs) isolated. The proportions of each Salmonella Enteritidis PT in layers and in humans were compared and the monthly distribution of the most common PT, isolated in both populations, was evaluated.

RESULTS: The time cluster analysis revealed significant clusters during the months May and June for layers and May, July, August, and September for humans. PT21, the most frequently isolated PT in both populations in 2005, seemed to be responsible of these significant clusters. PT4 was the second most frequently isolated PT. No significant difference was found for the monthly trend evolution of both PT in both populations based on parametric and non-parametric methods.

DISCUSSION AND CONCLUSION: A similar monthly trend of PT distribution in humans and layers during the year 2005 was observed. The time cluster analysis and the statistical significance testing confirmed these results. Moreover, the time cluster analysis showed significant clusters during the summer time and slightly delayed in time (humans after layers). These results suggest a common link between the prevalence of Salmonella Enteritidis in layers and the occurrence of the pathogen in humans. Phage typing was confirmed to be a useful tool for identifying temporal trends.

VL - 8 CP - 8 U1 - https://www.ncbi.nlm.nih.gov/pubmed/21492025?dopt=Abstract M3 - 10.1089/fpd.2010.0834 ER - TY - JOUR T1 - Development and inter-laboratory validation study of an improved new real-time PCR assay with internal control for detection and laboratory diagnosis of African swine fever virus. JF - J Virol Methods Y1 - 2011 A1 - Marylène Tignon A1 - Gallardo, Carmina A1 - Iscaro, Carmen A1 - Hutet, Evelyne A1 - Yves Van der Stede A1 - Kolbasov, Denis A1 - De Mia, Gian Mario A1 - Le Potier, Marie-Frédérique A1 - Bishop, Richard P A1 - Arias, Marisa A1 - F. Koenen KW - Actins KW - African Swine Fever KW - African Swine Fever Virus KW - Animals KW - Capsid Proteins KW - Clinical Laboratory Techniques KW - DNA Primers KW - DNA, Viral KW - European Union KW - Real-Time Polymerase Chain Reaction KW - Reference Standards KW - Reproducibility of Results KW - Sensitivity and Specificity KW - Swine KW - Veterinary Medicine KW - virology AB -

A real-time polymerase chain reaction (PCR) assay for the rapid detection of African swine fever virus (ASFV), multiplexed for simultaneous detection of swine beta-actin as an endogenous control, has been developed and validated by four National Reference Laboratories of the European Union for African swine fever (ASF) including the European Union Reference Laboratory. Primers and a TaqMan(®) probe specific for ASFV were selected from conserved regions of the p72 gene. The limit of detection of the new real-time PCR assay is 5.7-57 copies of the ASFV genome. High accuracy, reproducibility and robustness of the PCR assay (CV ranging from 0.7 to 5.4%) were demonstrated both within and between laboratories using different real-time PCR equipments. The specificity of virus detection was validated using a panel of 44 isolates collected over many years in various geographical locations in Europe, Africa and America, including recent isolates from the Caucasus region, Sardinia, East and West Africa. Compared to the OIE-prescribed conventional and real-time PCR assays, the sensitivity of the new assay with internal control was improved, as demonstrated by testing 281 field samples collected in recent outbreaks and surveillance areas in Europe and Africa (170 samples) together with samples obtained through experimental infections (111 samples). This is particularly evident in the early days following experimental infection and during the course of the disease in pigs sub-clinically infected with strains of low virulence (from 35 up to 70dpi). The specificity of the assay was also confirmed on 150 samples from uninfected pigs and wild boar from ASF-free areas. Measured on the total of 431 tested samples, the positive deviation of the new assay reaches 21% or 26% compared to PCR and real-time PCR methods recommended by OIE. This improved and rigorously validated real-time PCR assay with internal control will provide a rapid, sensitive and reliable molecular tool for ASFV detection in pigs in newly infected areas, control in endemic areas and surveillance in ASF-free areas.

VL - 178 CP - 1-2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/21946285?dopt=Abstract M3 - 10.1016/j.jviromet.2011.09.007 ER - TY - JOUR T1 - Tick-borne encephalitis virus seropositive dog detected in Belgium: screening of the canine population as sentinels for public health. JF - Vector Borne Zoonotic Dis Y1 - 2011 A1 - Sophie Roelandt A1 - Heyman, Paul A1 - De Filette, Marina A1 - Vene, Sirkka A1 - Yves Van der Stede A1 - Ann Brigitte Cay A1 - Tavernier, Paul A1 - Alexandre Dobly A1 - De Bosschere, Hendrik A1 - Vyt, Philip A1 - Meersschaert, Carole A1 - S. Roels KW - Animals KW - Antibodies, Viral KW - Belgium KW - Dog Diseases KW - Dogs KW - Encephalitis Viruses, Tick-Borne KW - Encephalitis, Tick-Borne KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Humans KW - Neutralization Tests KW - public health KW - Reagent Kits, Diagnostic KW - Sentinel Surveillance AB -

Tick-borne encephalitis virus (TBEV) is an important emerging tick-borne viral infection of humans and dogs in Europe. Currently, TBEV surveillance is virtually nonexistent in Belgium, which is considered nonendemic. A commercial enzyme-linked immunosorbent assay (ELISA) was adapted for the detection of TBEV-specific IgG-antibodies in canine sera. Serum samples of Belgian dogs were obtained from three diagnostic laboratories from Northern (n=688) and Southern Belgium (n=192). ELISA-positive and borderline samples were subjected to a TBEV rapid fluorescent focus inhibition confirmation test. One dog was confirmed TBEV seropositive. Several ELISA-positive and borderline sera underwent seroneutralization and hemagglutinin inhibition tests to rule out West Nile and Louping Ill viruses, but tested negative. The clinical history of the seropositive dog could not explain beyond doubt where and when TBEV infection was acquired. Further surveillance is necessary to determine whether this dog remains a single travel-related case or whether it represents an early warning of a possible future emergence of TBEV.

VL - 11 CP - 10 U1 - http://www.ncbi.nlm.nih.gov/pubmed/21919722?dopt=Abstract M3 - 10.1089/vbz.2011.0647 ER - TY - JOUR T1 - Classical swine fever: comparison of oronasal immunisation with CP7E2alf marker and C-strain vaccines in domestic pigs. JF - Vet Microbiol Y1 - 2010 A1 - Marylène Tignon A1 - Kulcsár, Gábor A1 - Andy Haegeman A1 - Barna, Timea A1 - Fábián, Katalin A1 - Lévai, Réka A1 - Yves Van der Stede A1 - Farsang, Attila A1 - Vrancken, Robert A1 - Belák, Katinka A1 - F. Koenen KW - Animals KW - Antibodies, Viral KW - Classical Swine Fever KW - Classical swine fever virus KW - Enzyme-Linked Immunosorbent Assay KW - Palatine Tonsil KW - Swine KW - Vaccination KW - Vaccines, Synthetic KW - Viral Vaccines KW - Virus Replication AB -

Effective oronasal vaccination against classical swine fever (CSF) is essential to achieve protection in wild boar. However the currently available live CSF vaccines, e.g. C-strain, do not allow serological differentiation between infected and vaccinated animals (DIVA). A modified live marker vaccine candidate (CP7E2alf) has been recently developed (Reimann et al., 2004). This communication reports the comparison of CP7E2alf and C-strain virus vaccines during 98 days following oronasal immunisation in domestic pigs. C-strain vaccine virus was consistently detected in tonsils of all (n=30) animals from 3 to 77 days post vaccination (dpv) and in blood (n=36) between 3 and 13dpv by CSFV-specific rRT-PCR. CP7E2alf virus RNA was detected in 6 animals slaughtered between 4 and 63dpv by a BVDV-specific rRT-PCR. The chimeric virus was not detected in blood samples. As detected by CSFV E2-specific antibody ELISA and virus neutralisation tests, seroconversion first occurred at 11dpv in the C-strain vaccinated group and between 11 and 15dpv in the CP7E2alf vaccinated group. The serological response was still present at 98dpv. The CP7E2alf serological response remained negative using the CSFV E(rns) ELISA whereas seroconversion occurred in the C-strain vaccinated group. In conclusion, the primary replication site of CP7E2alf vaccine virus was found to be the tonsils as in the C-strain and virulent field strains. Persistence of CP7E2alf in the tonsils was also demonstrated up to 63dpv. Both vaccines showed immunogenicity after oronasal administration in domestic pigs. In contrast to the C-strain, CP7E2alf vaccine allowed the use of DIVA approaches in serological tests. This study confirms CP7E2alf as a promising marker vaccine candidate for oronasal vaccination programmes to control CSF in domestic pigs and wild boar.

VL - 142 CP - 1-2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19857935?dopt=Abstract M3 - 10.1016/j.vetmic.2009.09.044 ER - TY - JOUR T1 - Influence of the incubation temperature and the batch components on the sensitivity of an enzyme-linked immunosorbent assay to detect Aujeszky's disease virus glycoprotein E (gE). JF - Rev Sci Tech Y1 - 2010 A1 - Ann Brigitte Cay A1 - Yves Van der Stede KW - Animals KW - Enzyme-Linked Immunosorbent Assay KW - Herpesvirus 1, Suid KW - Pseudorabies KW - Quality Control KW - Reference Values KW - Sensitivity and Specificity KW - Temperature KW - Viral Envelope Proteins AB -

Although licensed batches of an enzyme-linked immunosorbent assay (ELISA) for Aujeszky's disease virus (ADV) were used, and the assays were performed within an ISO/IEC 17025 accredited quality control system, certain routine runs of the ADV ELISA were not validated using the quality system criteria, even when all technical parameters were controlled. Incubation at different temperatures and batch composition were identified as parameters that could result in non-validated assays/runs. Therefore, the effect of incubation temperature and batch composition on the analytical sensitivity of the ELISA was investigated. The World Organisation for Animal Health (OIE) standard reference serum ADV1 was diluted 1:8 and tested in 94 different glycoprotein E ELISA runs performed with different batches and different incubation temperatures. The incubation temperature and batch components had a significant influence on the qualitative result for the OIE standard reference serum. An incubation temperature of at least 22 degrees C was recommended, based on the results of this analysis. Which of the batch components caused these differences in sensitivity was not investigated further.

VL - 29 CP - 3 U1 - http://www.ncbi.nlm.nih.gov/pubmed/21309455?dopt=Abstract ER - TY - JOUR T1 - Emergence of bluetongue serotypes in Europe, part 2: the occurrence of a BTV-11 strain in Belgium. JF - Transbound Emerg Dis Y1 - 2009 A1 - Kris De Clercq A1 - Mertens, P A1 - Ilse De Leeuw A1 - Oura, C A1 - Houdart, P A1 - Potgieter, A C A1 - Maan, S A1 - Hooyberghs, J A1 - Batten, C A1 - Vandemeulebroucke, E A1 - Wright, I M A1 - Maan, N A1 - Riocreux, F A1 - Sanders, A A1 - Yves Van der Stede A1 - Nomikou, K A1 - Raemaekers, M A1 - Bin-Tarif, A A1 - Shaw, A A1 - Henstock, M A1 - Bréard, E A1 - E. Dubois A1 - Gastaldi-Thiéry, C A1 - Zientara, S A1 - Verheyden, B A1 - Frank Vandenbussche KW - Animals KW - Antibodies, Viral KW - Belgium KW - Bluetongue KW - Bluetongue virus KW - Cattle KW - Cattle Diseases KW - cross-sectional studies KW - Dairying KW - Female KW - Population Surveillance KW - Pregnancy KW - Pregnancy Complications KW - RNA, Viral KW - Seasons KW - Sheep AB -

An EDTA-blood sample from a cow without clinical signs, which gave early birth to a newborn calf that died soon after delivery, was shown to be positive for bluetongue virus (BTV)-RNA using a group-specific real-time RT-PCR (RT-qPCR). In-house serotype-specific RT-qPCR assays for bluetongue virus serotype 1 (BTV-1), -6 and -8 all gave negative results. Subsequent assays were carried out using conventional (gel-based) RT-PCR primers for all 25 BTV serotypes and only two primer sets, both specific for BTV-11, gave bands of the expected size. The cDNAs generated were sequenced and comparisons of the genome segment 2 sequence with that of the modified 'live' vaccine strain of BTV-11 from South Africa showed 100% identity. A survey of all ruminants in a 1-km area around the first positive farm using a BTV-11 serotype-specific RT-qPCR revealed five other holdings with in total nine BTV-11 positive animals. A cross-sectional monitoring of dairy cattle in Belgium showed an overall prevalence of 3.8% on herd level and 0.2% on animal level. A BTV-11 has been introduced into the Belgian cattle herd during the 2008 vector season. The source of the infection and the way by which the virus was introduced are unknown.

VL - 56 CP - 9-10 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19909474?dopt=Abstract M3 - 10.1111/j.1865-1682.2009.01092.x ER - TY - JOUR T1 - Expert judgement in a risk assessment model for Salmonella spp. in pork: the performance of different weighting schemes. JF - Prev Vet Med Y1 - 2009 A1 - Boone, Ides A1 - Yves Van der Stede A1 - Bollaerts, Kaatje A1 - Messens, Winy A1 - Vose, David A1 - Daube, Georges A1 - Aerts, Marc A1 - Mintiens, Koen KW - Abattoirs KW - Animals KW - Belgium KW - Expert Testimony KW - Food Handling KW - Food Microbiology KW - Meat KW - Risk Factors KW - Salmonella Infections, Animal KW - Seroepidemiologic Studies KW - Swine KW - Swine Diseases AB -

A structured expert judgement study was carried out in order to obtain input parameters for a quantitative microbial risk assessment (QMRA) model. This model aimed to estimate the risk of human Salmonella infections associated with the consumption of minced pork meat. Judgements of 11 experts were used to derive subjective probability density functions (PDFs) to quantify the uncertainty on the model input parameters. The performance of experts as probability assessors was measured by the experts' ability to correctly and precisely provide estimates for a set of seed variables (=variables from the experts' area of expertise for which the true values were known to the analyst). Subsequently different weighting schemes or "decision makers" (DMs) were applied using Cooke's classical model in order to obtain combined PDFs as a weighted linear combination of the expert's individual PDFs. The aim of this study was to compare the performance of four DMs namely the equal weight DM (each expert's opinion received equal weight), the user weight DM (weights are determined by the expert's self-perceived level of expertise) and two performance-based DMs: the global weight DM and the item weight DM. Weights in the performance-based DMs were calculated based on the expert's calibration and information performance as measured on the set of seed variables. The item weight DM obtained the highest performance with a calibration score of 0.62 and an information score of 0.52, as compared to the other DMs. The weights of the performance-based DMs outperformed those of the best expert in the panel. The correlation between the scores for self-rating of expertise and the weights based on the experts' performance on the calibration variables was low and not significant (r=0.37, p=0.13). The applied classical model provided a rational basis to use the combined distributions obtained by the item weight DM as input in the QMRA model since this DM yielded generally more informative distributions for the variables of interest than those obtained by the equal weight and user weight DM. Attention should be paid to find adequate and relevant seed variables, since this is important for the validation of the results of the weighting scheme.

VL - 92 CP - 3 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19782415?dopt=Abstract M3 - 10.1016/j.prevetmed.2009.08.020 ER - TY - JOUR T1 - NUSAP method for evaluating the data quality in a quantitative microbial risk assessment model for Salmonella in the pork production chain. JF - Risk Anal Y1 - 2009 A1 - Boone, Ides A1 - Yves Van der Stede A1 - Bollaerts, Kaatje A1 - Vose, David A1 - Maes, Dominiek A1 - Dewulf, Jeroen A1 - Messens, Winy A1 - Daube, Georges A1 - Aerts, Marc A1 - Mintiens, Koen KW - Animals KW - Meat Products KW - Models, Theoretical KW - Risk Assessment KW - Salmonella KW - Swine AB -

The numeral unit spread assessment pedigree (NUSAP) system was implemented to evaluate the quality of input parameters in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. The input parameters were grouped according to four successive exposure pathways: (1) primary production (2) transport, holding, and slaughterhouse, (3) postprocessing, distribution, and storage, and (4) preparation and consumption. An inventory of 101 potential input parameters was used for building the QMRA model. The characteristics of each parameter were defined using a standardized procedure to assess (1) the source of information, (2) the sampling methodology and sample size, and (3) the distributional properties of the estimate. Each parameter was scored by a panel of experts using a pedigree matrix containing four criteria (proxy, empirical basis, method, and validation) to assess the quality, and this was graphically represented by means of kite diagrams. The parameters obtained significantly lower scores for the validation criterion as compared with the other criteria. Overall strengths of parameters related to the primary production module were significantly stronger compared to the other modules (the transport, holding, and slaughterhouse module, the processing, distribution, and storage module, and the preparation and consumption module). The pedigree assessment contributed to select 20 parameters, which were subsequently introduced in the QMRA model. The NUSAP methodology and kite diagrams are objective tools to discuss and visualize the quality of the parameters in a structured way. These two tools can be used in the selection procedure of input parameters for a QMRA, and can lead to a more transparent quality assurance in the QMRA.

VL - 29 CP - 4 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19192236?dopt=Abstract M3 - 10.1111/j.1539-6924.2008.01181.x ER - TY - JOUR T1 - Validation of two real-time RT-PCR methods for foot-and-mouth disease diagnosis: RNA-extraction, matrix effect, uncertainty of measurement and precision. JF - J Virol Methods Y1 - 2009 A1 - Goris, Nesya A1 - Frank Vandenbussche A1 - Herr, Cécile A1 - Villers, Jérôme A1 - Yves Van der Stede A1 - Kris De Clercq KW - Animals KW - blood KW - Diagnostic Errors KW - Foot KW - Foot-and-Mouth Disease KW - Foot-and-Mouth Disease Virus KW - Reverse Transcriptase Polymerase Chain Reaction KW - RNA, Viral KW - Sensitivity and Specificity AB -

Real-time reverse transcription polymerase chain reaction (rRT-PCR) assays are being used routinely for diagnosing foot-and-mouth disease virus (FMDV). Although most laboratories determine analytical and diagnostic sensitivity and specificity, a thorough validation in terms of establishing optimal RNA-extraction conditions, matrix effect, uncertainty of measurement and precision is not performed or reported generally. In this study, different RNA-extraction procedures were compared for two FMDV rRT-PCRs. The NucleoSpin columns available commercially combined high extraction efficiency with ease-of-automation. Furthermore, six different FMDV-negative matrices were spiked with a dilution series of FMDV SAT1 ZIM 25/89. Compared to cell-culture-spiked viral control samples, no matrix effect on the analytical sensitivity was found for blood or foot epithelium. Approximately 1log(10) reduction in detection limit was noted for faecal and tongue epithelium samples, whereas a 3log(10) decrease was observed for spleen samples. By testing the same dilution series in duplicate on 10 different occasions, an estimation of uncertainty of measurement and precision was obtained using blood as matrix. Both rRT-PCRs produced highly precise results emphasising their potential to replace conventional virological methods. The uncertainty measurement, as described in this study, proved to be a useful tool to evaluate the probability of making a wrong decision.

VL - 160 CP - 1-2 U1 - http://www.ncbi.nlm.nih.gov/pubmed/19447138?dopt=Abstract M3 - 10.1016/j.jviromet.2009.05.005 ER - TY - JOUR T1 - Application of a Commercial Real-Time RT-PCR Assay for Surveillance of Classical Swine Fever: Evaluation by Testing Sequential Tissue and Blood Samples JF - The Open Veterinary Science Journal Y1 - 2008 A1 - Marylène Tignon A1 - G. Kulcsar A1 - K. Belak A1 - Andy Haegeman A1 - T. Barna A1 - K. Fabian A1 - R. Levai A1 - A. Farsang A1 - Yves Van der Stede A1 - R. Vrancken A1 - F. Koenen AB -

The applicability of the commercial TaqVet CSFV real-time RT-PCR assay (TaqVet CSF) as a diagnostic tool for herd surveillance of classical swine fever (CSF) was evaluated in an experimental setup on a group of 28 pigs infected with a moderately virulent classical swine fever virus (CSFV) strain of wild boar origin (‘11722-WIL’). Based on the viral distribution determined in tissue by the real-time RT-PCR assay (rRT-PCR), the tonsils were found the most suitable tissue for CSFV detection. In the tonsils, the viral genome was detected during the incubation phase, as early as 2 days post infection (dpi), and during the clinical phase until the end of the experiment (24 dpi). In blood, viral RNA detection was delayed by 2 days compared to the corresponding tonsils. Virus was irregularly detected in muscles, indicating the poor reliability of meat for CSFV monitoring. For surveillance programmes, the effectiveness of the rRT-PCR kit was also evaluated on blood samples collected at the scale of the animal group and compared to the individual diagnosis based on analysis of tonsils. The present study indicated that, at the very early stages of infection, comparable detection efficiency was achieved by using large numbers of blood samples or smaller number of tonsils. The increased size of sampling is necessary to compensate the lower viral load observed in blood. Based on these results, testing of blood can be proposed as an acceptable alternative to tonsils for herd surveillance with the TaqVet CSF kit, providing that extended sampling is undertaken.

VL - 2 CP - 1 M3 - 10.2174/1874318800802010104 ER - TY - JOUR T1 - Indirect foot-and-mouth disease vaccine potency testing based on a serological alternative. JF - Vaccine Y1 - 2008 A1 - Goris, Nesya A1 - Willems, Tom A1 - Diev, Vyacheslav I A1 - Merkelbach-Peters, Petra A1 - Vanbinst, Tine A1 - Yves Van der Stede A1 - Kraft, Horst-Peter A1 - Zakharov, Valery M A1 - Borisov, Vladimir V A1 - Nauwynck, Hans J A1 - Haas, Bernd A1 - Kris De Clercq KW - Animals KW - Antibodies, Viral KW - Cattle KW - Enzyme-Linked Immunosorbent Assay KW - Foot-and-Mouth Disease KW - Logistic Models KW - Neutralization Tests KW - Predictive Value of Tests KW - Reproducibility of Results KW - Roc Curve KW - Statistics as Topic KW - Viral Vaccines AB -

Foot-and-mouth disease (FMD) vaccine potency testing has historically been performed by experimentally infecting vaccinated cattle. A few alternative approaches to the in vivo challenge test based on the correlation between serum titres of primo-vaccinated cattle and protection against infection have been proposed, but none have been accepted by the European Pharmacopoeia (Ph.Eur.) due to the lack of statistical power and the pooling of data over time. The present study addresses these issues and presents data of 150 cattle vaccinated according to Ph.Eur. standards. Four laboratories took part in the serological testing and different serological assays were used, including virus neutralisation assays and ELISA formats. Models correlating specific anti-FMD virus antibody titres to protection were built using logistic regression followed by Receiver Operating Characteristic (ROC) analysis. The best models accurately predicted the in vivo protection status in 80.0% of the cases. Although differences were observed between laboratories and assays used, the majority of antibody pass-levels, determined using ROC analysis, corresponded to at least 75.0% probability of protection. The indirect potency assessment procedure proposed is at least as precise (repeatability=65.8%, reproducibility=60.7%) as the in vivo test, can be standardised and results in a quantitative PD50 value. The validity of the procedure was also demonstrated.

VL - 26 CP - 31 U1 - http://www.ncbi.nlm.nih.gov/pubmed/18555565?dopt=Abstract M3 - 10.1016/j.vaccine.2008.05.013 ER -