TY - JOUR T1 - Assessing evidence of a potential Salmonella transmission across the poultry food chain. JF - Zoonoses Public Health Y1 - 2022 A1 - Mickael Cargnel A1 - Maria‐Eleni Filippitzi A1 - Dieter Van Cauteren A1 - Wesley Mattheus A1 - N Botteldoorn A1 - Cambier,L. A1 - Sarah Welby AB -

Enhanced Salmonella surveillance programmes in poultry were implemented in all European Member States, with minimum prevalence targets for a list of targeted serotypes to safeguard food and public health. Based on the Belgian Salmonella surveillance programme and focusing on poultry, the overarching aim of this study was to highlight possible Salmonella transmissions across the food chain (FC). For this purpose, firstly, the prevalence patterns of Salmonella (targeted and the most prevalent non-targeted) serotypes along the FC were described over time. Secondly, the effectiveness of the control measures against vertical transmission (breeders to 1-day-old broiler and layer chicks) was indirectly assessed by looking into the odds of targeted serotypes detection. Thirdly, it was appraised if Salmonella prevalence can significantly increase during broilers and layers production. In addition, it was tested if being tested negative at the end of production in broilers when tested positive at the entrance is serotype dependent (targeted vs. non-targeted serotypes). Results showed that, firstly, the prevalence patterns of the listed serotypes were inconstant over time and across the FC. Secondly, the odds of Salmonella targeted serotype detection in 1-day-old broiler and in 1-day-old layer flocks were lower than in breeder flocks while, thirdly, infection during broiler and layer production can lead to significant increase in positivity in subsequent samples. Finally, being infected by a targeted or by non-targeted serotype at the entrance of the flock poorly reflects the Salmonella status at the end of production. Note that this study did not make a distinction between the different sources of contamination and the effects of sampling methods and isolation methods should be subject to further investigation.

M3 - 10.1111/zph.12998 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 - Quantitative decision making in animal health surveillance: Bovine Tuberculosis Surveillance in Belgium as case study. JF - Transbound Emerg Dis Y1 - 2021 A1 - Sarah Welby A1 - Mickael Cargnel A1 - Saegerman, Claude AB -

Despite eradication and control measures applied across Europe, bovine tuberculosis (bTB) remains a constant threat. In Belgium, after several years of official bTB-free status, routine movement testing, as currently practiced, revealed itself inadequate to detect some herds affected by sporadic breakdowns. The aim of this study was to assess different surveillance system components that strike a balance between cost and effectiveness and to identify sustainable alternatives, which substantiate a bTB-free claim while ensuring early detection and acceptance by various animal health stakeholders. For this pupose, a stochastic iteration model was used to simulate the current surveillance system's expected performance in terms of detection sensitivity and specificity. These results were then descriptively compared with observed field results. Second, the cost and effectiveness of simulated alternative surveillance components were quantified. Sensitivity analyses were performed to measure key assumptions' impacts (i.e. regarding diagnostic tests and true prevalence). The results confirmed discrepancies between the observed and simulated expected performance of bTB surveillance in Belgium. Second, simulated alternatives showed that interferon gamma (IFN-γ) and serological testing with antibody-enzyme linked immunosorbent assay (Ab-ELISA) targeting at-risk herds would enable an increase in the overall cost effectiveness (sensitivity and specificity) of the Belgian bTB surveillance system. Sensitivity analyses showed that results remained constant despite the modification of some key assumptions. While the performance of the ongoing bTB surveillance system in Belgium was questionable at the time of the study, this exercise highlighted that not only sensitivity but specificity also are key drivers of surveillance performance. The quantitative approach, taking into consideration various stakeholders' needs and priorities, revealed itself to be a useful tool in allowing evidence-based decision making for future tuberculosis surveillance in Belgium, in line with the international standards.

M3 - 10.1111/tbed.14269 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 - Associations between a decreased veterinary antimicrobial use and resistance in commensal Escherichia coli from Belgian livestock species (2011–2015) JF - Preventive Veterinary Medicine Y1 - 2018 A1 - Bénédicte Callens A1 - Mickael Cargnel A1 - Sarrazin, Steven A1 - Dewulf, Jeroen A1 - Bart Hoet A1 - Vermeersch, Katie A1 - P Wattiau A1 - Sarah Welby VL - 157 M3 - 10.1016/j.prevetmed.2017.10.013 ER - TY - JOUR T1 - Risk Classification of Zoonotic Microorganisms: Development of a One Health Approach Tool Applied to HPAI A H5N1 Viruses JF - Applied Biosafety Y1 - 2018 A1 - Aline Baldo A1 - Sarah Welby A1 - Chuong Dai Do Thi A1 - Amaya Leunda A1 - Philippe Herman A1 - Didier Breyer M3 - 10.1177/1535676018799094 ER - TY - JOUR T1 - Seroprevalence and risk factors related to small ruminant lentivirus infections in Belgian sheep and goats. JF - Prev Vet Med Y1 - 2018 A1 - Michiels, Rodolphe A1 - Van Mael, Eva A1 - Quinet, Christian A1 - Sarah Welby A1 - Ann Brigitte Cay A1 - Nick De Regge KW - Animals KW - Arthritis-Encephalitis Virus, Caprine KW - Belgium KW - Goat Diseases KW - Goats KW - Lentivirus Infections KW - prevalence KW - Risk Factors KW - Seroepidemiologic Studies KW - Sheep KW - Sheep Diseases KW - Visna-maedi virus AB -

Maedi-Visna virus (MVV) and caprine arthritis encephalitis virus (CAEV) are two prototype members of the group of small ruminant lentiviruses (SRLVs). Both result in progressive and persistent infections of sheep and goats that impact animal health and cause economic losses. In Belgium, the sheep and goat sector is small and consists mostly of hobbyist farmers keeping few animals. A voluntary control program however exists, but less than 2% of the farmers participate to the program. The current lack of SRLV seroprevalence data and knowledge on risk factors related to SRLV seropositivity in this hobbyist sector makes it difficult to evaluate the risk of SRLV transmission from non-certified to SRLV free certified farms. We performed a nationwide SRLV seroprevalence study based on a stratified sampling proportional to the number of sheep and goat holders per province. Randomly selected sheep and goat owners were invited to participate and subject to a short questionnaire to collect information about flock size, animal health condition, age, flock constitution and housing conditions. Samples were collected from maximum 7 animals per farm and tested in a commercial ELISA. In total, we received samples from 87 sheep and 76 goat farms. Sheep flocks showed an overall seroprevalence of 9% (CI : 5-15) and a between-herd seroprevalence of 17% (CI :11-27). Seroprevalence at animal level in goat flocks was 6% (CI : 3-12) and the between-herd seroprevalence was 13% (CI : 7-23). Multiple sheep and goat breeds were found SRLV seropositive. Answers provided during the questionnaire confirmed the mostly hobbyist nature of the sector and showed that more than 65% of sheep and goat farmers had never heard of the disease. The only risk factor found to be related to SRLV seroprevalence was flock size. Herds of more than 10 goats had significantly higher chance to harbor seropositive animals (OR: 4.36; CI: 1.07; 17.73). In conclusion, it was shown that participants to the SRLV free certification program are at risk for reintroduction of the disease in their herds since SRLVs are present on about 15%-20% of non-certified farms. Except from flock size, no clear risk factors were found that are helpfull to identify flocks at risk. Greater effort should be made to inform sheep and goat farmers about the existence and consequences of this disease in order to promote the voluntary control program and further reduce the disease prevalence.

VL - 151 M3 - 10.1016/j.prevetmed.2017.12.014 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 - Field performance of six Mycobacterium avium subsp. paratuberculosis antigens in a 20 h interferon gamma release assay in Belgium JF - Veterinary Immunology and Immunopathology Y1 - 2017 A1 - Dernivoix, Kathy A1 - Virginie Roupie A1 - Sarah Welby A1 - Sophie Roelandt A1 - Viart, Sophie A1 - Letesson, Jean-Jacques A1 - Wattiez, Ruddy A1 - Huygen, Kris A1 - Govaerts, Marc KW - IFN-γ KW - Johne’s disease KW - Mycobacterium avium subsp. paratuberculosis KW - Paratuberculosis VL - 189 M3 - 10.1016/j.vetimm.2017.05.008 ER - TY - JOUR T1 - Age- and strain-dependent differences in the outcome of experimental infections of domestic pigs with wild boar pseudorabies virus isolates. JF - J Gen Virol Y1 - 2016 A1 - Verpoest, Sara A1 - Ann Brigitte Cay A1 - Willem Van Campe A1 - Laurent Mostin A1 - Sarah Welby A1 - Favoreel, Herman A1 - Nick De Regge KW - Animals KW - Disease Models, Animal KW - Disease Transmission, Infectious KW - Europe KW - Herpesvirus 1, Suid KW - Pseudorabies KW - Sus scrofa KW - Swine KW - Swine Diseases KW - Treatment Outcome AB -

Although pseudorabies virus (PRV) has been eradicated in domestic swine in many countries, its presence in wild boars remains a threat for a reintroduction into the currently unprotected swine population. To assess the possible impact of such a reintroduction in a naive herd, an in vivo infection study using two genetically characterized wild boar PRV isolates (BEL24043 and BEL20075) representative for wild boar strains circulating in south-western and central Europe and the virulent NIA3 reference strain was performed in 2- and 15-week-old domestic pigs. Our study revealed an attenuated nature of both wild boar strains in 15-week-old pigs. In contrast, it showed the capacity of strain BEL24043 to induce severe clinical symptoms and mortality in young piglets, thereby confirming that the known age dependency of disease outcome after PRV infection also holds for wild boar isolates. Despite the absence of clinical disease in 15-week-old sows, both wild boar PRV strains were able to induce seroconversion, but to a different extent. Importantly, differences in infection and transmission capacity of both strains were observed in 15-week-old sows. Strain BEL24043 induced a more prolonged and disseminated infection than strain BEL20075 and was able to spread efficiently to contact animals, indicative of its capacity to induce a sustained infection. In conclusion, it was shown that a reintroduction of a wild boar isolate into the domestic swine population could have serious economic consequences due to the induction of clinical symptoms in piglets and by jeopardizing the PRV-negative status.

VL - 97 CP - 2 U1 - https://www.ncbi.nlm.nih.gov/pubmed/26589961?dopt=Abstract M3 - 10.1099/jgv.0.000347 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 - Prevalence of Mycoplasma gallisepticum and Mycoplasma synoviae in commercial poultry, racing pigeons and wild birds in Belgium. JF - Avian Pathol Y1 - 2016 A1 - Michiels, Tinne A1 - Sarah Welby A1 - Vanrobaeys, Mia A1 - Quinet, Christian A1 - Rouffaer, Lieze A1 - Lens, Luc A1 - Martel, An A1 - Butaye, Patrick KW - Animals KW - Belgium KW - Birds KW - Columbidae KW - Enzyme-Linked Immunosorbent Assay KW - Female KW - Male KW - Mycoplasma gallisepticum KW - Mycoplasma Infections KW - Mycoplasma synoviae KW - Poultry KW - Poultry Diseases KW - prevalence KW - Real-Time Polymerase Chain Reaction AB -

Mycoplasma gallisepticum is the most important pathogenic avian Mycoplasma species and causes chronic respiratory disease in poultry. In addition, the prevalence of Mycoplasma synoviae is of increasing concern in several EU member states. We investigated the prevalence of M. gallisepticum in commercial poultry (5220 layers, 1224 broilers and 1020 meat turkeys), 56 racing pigeons and 890 wild birds (Order Anseriformes, Galliformes, Pelecaniformes, Accipitriformes, Gruiformes, Charadriiformes, Columbiformes, Strigiformes, Falconiformes and Passeriformes). Broilers and wild birds were also evaluated for Mycoplasma synoviae. Dependent on the bird lifespan and the nature of the sample, different diagnostic tests were used including the rapid plate agglutination test, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction and real-time polymerase chain reaction. A low prevalence of M. gallisepticum was found in both layers (0.9%; 95% CI: 0.7-1.2%) and broilers (2.7%; 95% CI: 1.9-3.8%) possibly due to reduced vertical transmission by breeder farms, which are under official surveillance. None of the samples from turkeys or racing pigeons tested positive. In wild birds, we found five birds were positive (1.7%; 95% CI: 0.7-3.9%): one wood pigeon, two grey herons, one mallard and one Eurasian magpie. For M. synoviae a high prevalence was found in broilers (12.9%: 95% CI: 11.1-14.9%). Four samples collected by hunters gave a positive result for M. synoviae (4%: 95% CI: 1.6-9.8%): one carrion crow and three wood pigeons. In addition, 12 house sparrows were found to be positive (3%; 95% CI: 1.7-5.2%). Wild birds probably play a limited role as a reservoir but we cannot exclude a possible impact on transmission of Mycoplasmas.

VL - 45 CP - 2 U1 - https://www.ncbi.nlm.nih.gov/pubmed/26814376?dopt=Abstract M3 - 10.1080/03079457.2016.1145354 ER - TY - JOUR T1 - Quantification of rHVT-F genome load in feather follicles by specific real-time qPCR as an indicator of NDV-specific humoral immunity induced by day-old vaccination in SPF chickens. JF - Avian Pathol Y1 - 2015 A1 - Fabienne Rauw A1 - Steven Van Borm A1 - Sarah Welby A1 - Ngabirano, E A1 - Gardin, Y A1 - Palya, V A1 - Bénédicte Lambrecht KW - Animals KW - Bursa of Fabricius KW - Chickens KW - Enzyme-Linked Immunosorbent Assay KW - Feathers KW - Fluorescence KW - Genetic Load KW - Herpesvirus Vaccines KW - Immunity, Humoral KW - Lung KW - Models, Genetic KW - Newcastle Disease KW - Oligonucleotides KW - Real-Time Polymerase Chain Reaction KW - Specific Pathogen-Free Organisms KW - Turkey KW - Vaccination AB -

The purpose of this study was to look for a reliable molecular method for confirmation of uptake of recombinant turkey herpesvirus vaccine against Newcastle disease (rHVT-F) and for use as a valuable prediction tool of Newcastle disease virus (NDV)-specific immune response in chickens deprived of maternally derived antibody (MDA). A quantitative real-time polymerase chain reaction (real-time qPCR) specific to rHVT-F was developed. The method was applied to various tissue samples taken from specific pathogen free (SPF) chickens experimentally inoculated at day-old with one dose of rHVT-F vaccine over a 6-week period. Among the tested tissues, the rHVT-F vaccine was detected predominantly in the bursa of Fabricius (BF) and the lung for the first week, followed by a progressive decline from 9 days onwards. Then, an increase of genome load was observed in the feather follicles (FF) with a peak at 2 weeks, rising to a level almost 10(3)-fold greater than in the other tissues. Importantly, the rHVT-F genome load in FF appeared to be strongly correlated to the humoral immunity specific to NDV as evaluated by haemagglutination inhibition (HI) test and NDV-specific IgG, IgM and IgA ELISAs. This is the first report of quantification of rHVT-F vaccine in FF and its correlation with the induction of ND-specific immune response in chickens with no MDA. Our data indicate that the application of this real-time qPCR assay on FF samples taken from chickens in the field may be used to confirm rHVT-F vaccine administration and uptake with the important added benefit of offering a non-disruptive sampling procedure.

VL - 44 CP - 3 U1 - https://www.ncbi.nlm.nih.gov/pubmed/25687165?dopt=Abstract M3 - 10.1080/03079457.2015.1018869 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 - Biosafety risk assessment and management of laboratory-derived influenza A (H5N1) viruses transmissible in ferrets JF - Applied Biosafety Y1 - 2013 A1 - Aline Baldo A1 - Amaya Leunda A1 - Chuong Dai Do Thi A1 - Didier Breyer A1 - Katia Pauwels A1 - Sarah Welby A1 - Van Vaerenbergh, Bernadette A1 - Philippe Herman KW - biosafety KW - Highly pathogenic avian influenza A (H5N1) virus KW - Risk Assessment AB - Highly pathogenic avian influenza (HPAI) A (H5N1) viruses occasionally infect humans, but currently do not transmit efficiently among them. However, the risk for human pandemic influenza is a major concern should these viruses acquire the capacity for human-to-human transmission and retain their current virulence. Recently, two research teams have succeeded in modifying HPAI A (H5N1) viruses in such a way that they could be efficiently transmitted by respiratory route between ferrets, the experimental model for studying influenza virus transmission. In this article, the authors discuss the risk assessment of these mutant HPAI A (H5N1) viruses in the context of the European Union regulatory framework and recommend that laboratory-derived HPAI A (H5N1) viruses transmissible in ferrets should be handled in biosafety level 3 (BSL-3) facilities with some additional biosafety measures. VL - 18 CP - 1 M3 - http://journals.sagepub.com/doi/pdf/10.1177/153567601301800102 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 - 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 - Seroprevalence of Neospora caninum, paratuberculosis and Q fever in cattle in Belgium in 2009-2010. JF - Vet Rec Y1 - 2012 A1 - Vangeel, I A1 - Estelle Méroc A1 - S Roelandt A1 - Sarah Welby A1 - Riocreux, F A1 - Driessche, E V A1 - Schoubroeck, L V A1 - Czaplicki, G A1 - Quinet, C A1 - Hooyberghs, J A1 - Houdart, P A1 - Y Van Der Stede KW - Animals KW - Belgium KW - Cattle KW - Cattle Diseases KW - Coccidiosis KW - Neospora KW - Paratuberculosis KW - Q Fever KW - Seroepidemiologic Studies VL - 171 CP - 19 U1 - https://www.ncbi.nlm.nih.gov/pubmed/22952130?dopt=Abstract M3 - 10.1136/vr.101016 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 - Further evidence of antigenic drift and protective efficacy afforded by a recombinant HVT-H5 vaccine against challenge with two antigenically divergent Egyptian clade 2.2.1 HPAI H5N1 strains. JF - Vaccine Y1 - 2011 A1 - Fabienne Rauw A1 - Palya, V A1 - Steven Van Borm A1 - Sarah Welby A1 - Tatar-Kis, T A1 - Gardin, Y A1 - Dorsey, K Moore A1 - Aly, M M A1 - Hassan, M K A1 - Soliman, M A A1 - Bénédicte Lambrecht A1 - Thierry van den Berg KW - Animals KW - Antibodies, Viral KW - Chickens KW - Drug Carriers KW - Genetic Vectors KW - Hemagglutination Inhibition Tests KW - Hemagglutinin Glycoproteins, Influenza Virus KW - Herpesvirus 1, Meleagrid KW - Immunization, Secondary KW - Influenza A Virus, H5N1 Subtype KW - Influenza A Virus, H5N2 Subtype KW - Influenza in Birds KW - Influenza Vaccines KW - Vaccination KW - Vaccines, Inactivated KW - Vaccines, Synthetic AB -

In this study, we have compared the protection afforded by a recombinant turkey herpesvirus vaccine expressing the H5 gene from a clade 2.2 H5N1 strain (rHVT-H5) and a Mexican-origin H5N2 inactivated vaccine, alone or in combination, against two antigenically divergent H5N1 Egyptian strains isolated in 2007 and 2008. Our results confirm the existence of a major antigenic drift among the Egyptian H5N1 strains such that, although protection against the "classical" 2007 HPAI H5N1 Egyptian strain could be obtained with both types of vaccines, only vaccination with the rHVT-H5 vaccine protected against challenge with the "variant" 2008 HPAI H5N1 Egyptian strain.

VL - 29 CP - 14 U1 - https://www.ncbi.nlm.nih.gov/pubmed/21292007?dopt=Abstract M3 - 10.1016/j.vaccine.2011.01.048 ER - TY - JOUR T1 - Redesigning the serological surveillance program for notifiable avian influenza in Belgian professional poultry holdings. JF - Avian Dis Y1 - 2010 A1 - Sarah Welby A1 - Thierry van den Berg A1 - Sylvie Marché A1 - Houdart, Philippe A1 - Hooyberghs, Jozef A1 - Mintiens, Koen KW - Agriculture KW - Animals KW - Belgium KW - Communicable Disease Control KW - Disease Notification KW - Influenza in Birds KW - National Health Programs KW - Poultry KW - Seroepidemiologic Studies AB -

This study was aimed at redesigning the Belgian active surveillance program for domestic birds in professional poultry holdings based on a risk analysis approach. A stochastic quantitative analysis, combining all data sources, was run to obtain sensitivity estimates for the detection of an infected bird in the different risk groups identified. An optimal number of holdings for each risk group was then estimated on the basis of the different sensitivities obtained. This study proved to be a useful tool for decision makers, providing insight on how to reallocate the total amount of samples to be taken in the coming year(s) in Belgium, thus optimizing the field resources and improving efficiency of disease surveillance such as required by the international standards.

VL - 54 CP - 1 Suppl U1 - https://www.ncbi.nlm.nih.gov/pubmed/20521701?dopt=Abstract M3 - 10.1637/8749-033009-Reg.1 ER - TY - JOUR T1 - Identification of risk factors for the prevalence and persistence of Salmonella in Belgian broiler chicken flocks. JF - Prev Vet Med Y1 - 2009 A1 - Namata, Harriet A1 - Sarah Welby A1 - Aerts, Marc A1 - Faes, Christel A1 - Abrahantes, José Cortiñas A1 - Hein Imberechts A1 - Vermeersch, Katie A1 - Hooyberghs, Jozef A1 - Estelle Méroc A1 - Mintiens, Koen KW - Animal Husbandry KW - Animals KW - Belgium KW - Chickens KW - Poultry Diseases KW - prevalence KW - Risk Factors KW - Salmonella Infections, Animal KW - Surveys and Questionnaires AB -

According to the European Food Safety Authority, salmonellosis is still one of the main causes of infectious foodborne gastroenteritis in humans. Broilers are an important source of salmonellosis after eggs and pork. Between 1987 and 1999 the trend of human salmonellosis incidence in Belgium increased constantly. However, from 2000 until 2005 a decrease in human cases was observed, probably following the sanitary measures implemented in the poultry breeder and laying sector. In order to decrease human infections it is essential to tackle the problem at the farm level to minimize cross-contamination from farm to fork. This paper seeks to answer two questions: (i) given the Salmonella status of the farm at a certain occasion (equal to the sampling time of the flock), what are the risk factors that the farm will be Salmonella positive at a following occasion? And (ii) what are the risk factors for a farm to be persistently positive for two consecutive flocks? We used surveillance data on 6824 broiler flocks studied for Salmonella infectivity from 2005 to 2006 in Belgium. The farms were tested regularly (3 weeks before slaughter of each broiler flock) for the presence of Salmonella based on multiple faecal samples per flock on a farm yielding clustered data. Generalized estimating equations, alternating logistic regression models, and random-intercept logistic regression models were employed to analyse these correlated binary data. Our results indicated that there are many factors that influence Salmonella risk in broiler flocks, and that they interact. Accounting for interactions between risk factors leads to an improved determination of those risk factors that increase infection with Salmonella. For the conditional analysis, the risk factors found to increase the risk of Salmonella infection on a farm at a current occasion given the previous Salmonella status included: Salmonella infection of day-old chicks (of the current flock); a previously infected flock even though the farm was equipped with a hygiene place to change clothes prior to entering the broiler house; having temporary workmen when there was a separation between birds of different species; and separating birds of different species in the Walloon region relative to the Flanders region. Sanitary measures such as a cleaning and disinfecting procedure conducted by an external cleaning firm, applying the all-in all-out procedure, and hand washing decreased the risk despite their interaction with other factors. From the joint analysis, the most important factors identified for increased risk for persistent Salmonella on a farm involved the interaction between having temporary workmen when there were poultry or farmers in contact with foreign poultry or persons, and the interaction between having temporary workmen when there were poultry or farmers in contact with external poultry or persons.

VL - 90 CP - 3-4 U1 - https://www.ncbi.nlm.nih.gov/pubmed/19467722?dopt=Abstract M3 - 10.1016/j.prevetmed.2009.03.006 ER -