Abortions and perinatal mortalities (APM) substantially affect cattle industry efficiency. Various infectious and noninfectious factors have been associated with bovine APM worldwide. Infections are often considered pivotal due to their abortifacient potential, leading laboratories to primarily investigate relevant infectious agents for APM cases. Some infectious causes, such as Brucella abortus, have also a zoonotic impact, necessitating monitoring for both animal and human health. However, underreporting of bovine APM is a global issue, affecting early detection of infectious and zoonotic causes. Previous studies identified factors influencing case submission, but regional characteristics may affect results. In Belgium, farmers are obliged to report cases of APM within the context of a national brucellosis monitoring program. The inclusion criteria for this monitoring program cover abortions (gestation length of 42-260 d) and perinatal mortalities of (pre) mature calves following a gestation length of more than 260 d, which were stillborn or died within 48 h after birth. The objective of the present study was to describe the evolution in submission of APM cases within a mandatory abortion monitoring program in relation to subsidized initiatives in the northern part of Belgium. Based on the proportion of APM submissions versus the proportion of bovine reproductive females, an APM proportion (APMPR) was calculated, and factors at both animal and herd level that may influence this APMPR were explored by using linear models. This evaluation revealed that the APMPR increased with the introduction of an extensive analytical panel of abortifacient agents and a free on -farm sample collection from 0.44% to 0.94%. Additionally, an increase of the APMPR was associated with an outbreak of an emerging abortifacient pathogen (Schmallenberg virus; 1.23%), and the introduction of a mandatory eradica tion program for bovine viral diarrhea virus (BVDv; 1.20%). The APMPR was higher in beef compared with dairy cattle, and it was higher in winter compared with fall, spring, and summer. Smaller herds categorized in the first quartile had a higher APMPR compared with larger herds. Herds that submitted an APM in the previous year had a higher APMPR in the next year compared with herds without an APM submission. Finally, herds for which there was evidence of the presence of BVDv had a higher APMPR compared with herds without evidence of the presence of BVDv. In conclusion, the number of APM submissions increased after the introduction of a free on -farm sample collection and an extensive pathogen screening panel. Production type (beef), season (winter), smaller herd size, previous APM, and presence of BVDv seemed to have a positive effect on APMPR. However, even under mandatory circumstances, APM still seems to be underreported, since the APMPR was lower than the expected minimal rate of 2%. Therefore, further research is necessary to identify the drivers that convince farmers to submit APM cases to improve submission rates and ensure an efficient monitoring program for APM and eventually associated zoonotic pathogens.

A plethora of infectious and non-infectious causes of bovine abortion and perinatal mortalities (APM) have been reported in literature. However, due to financial limitations or a potential zoonotic impact, many laboratories only offer a standard analytical panel, limited to a preestablished number of pathogens. To improve the cost-efficiency of laboratory diagnostics, it could be beneficial to design a targeted analytical approach for APM cases, based on maternal and environmental characteristics associated with the prevalence of specific abortifacient pathogens. The objective of this retrospective observational study was to implement a machine learning pipeline (MLP) to predict maternal and environmental factors associated with infectious APM. Our MLP based on a greedy ensemble approach incorporated a standard tuning grid of four models, applied on a dataset of 1,590 APM cases with a positive diagnosis that was achieved by analyzing an extensive set of abortifacient pathogens. Production type (dairy/beef), gestation length, and season were successfully predicted by the greedy ensemble, with a modest prediction capacity which ranged between 63 to 73%. Besides the predictive accuracy of individual variables, our MLP hierarchically identified predictor importance causes of associated environmental/maternal characteristics of APM. For instance, in APM cases that happened in beef cows, season at APM (spring/summer) was the most important predictor with a relative importance of 24%. Furthermore, at the last trimester of gestation Trueperella pyogenes and Neospora caninum were the most important predictors of APM with a relative importance of 22 and 17%, respectively. Interestingly, herd size came out as the most relevant predictor for APM in multiparous dams, with a relative importance of 12%. Based on these and other mix of predicted environmental/maternal and pathogenic potential causes, it could be concluded that implementing our MLP may be beneficial to design a more cost-effective, case-specific diagnostic approach for bovine APM cases at the diagnostic laboratory level.

This study aimed to investigate the presence of Chlamydia spp. and Parachlamydia acanthamoebae in bovine placental tissue originating from abortion and non-abortion cases in Belgium. Placentas of 164 late term bovine abortions (last trimester of gestation) and 41 non-abortion (collected after calving) cases were analysed by PCR for Chlamydia spp., Chlamydia abortus, C. psittaci and P. acanthamoebae. Additionally, a subset of 101 (75 abortion and 26 non-abortion cases) of these placenta samples were also analysed by histopathology to detect possible Chlamydia-induced lesions. In 5.4% (11/205) of the cases, Chlamydia spp. were detected, and three of those cases were positive for C. psittaci. Parachlamydia acanthamoebae was detected in 36% (75/205) of the cases, being 44% (n = 72) in abortions and 7.3% (n = 3) in non-abortions cases (p < .001). None of the cases was positive for C. abortus. Purulent and/or necrotizing placentitis with or without vasculitis was observed in 18.8% (19/101) of the histopathologically analysed placenta samples. In 5.9% (6/101) of the cases, placentitis was observed along with vasculitis. In the abortion cases, 24% (18/75) of the samples showed purulent and/or necrotizing placentitis, while purulent and/or necrotizing placentitis was visible in 3.9% (1/26) of the non-abortion cases. Placental lesions of inflammation and/or necrosis were present in 44% (15/34) of the cases where P. acanthamoebae was detected, while inflammation and/or necrosis was present in 20.9% (14/67) of the negative cases (p < .05). The detection of Chlamydia spp. and especially P. acanthamoebae, in combination with correlated histological lesions such as purulent and/or necrotizing placentitis and/or vasculitis in placental tissue following abortion, suggests a potential role of this pathogen in cases of bovine abortion in Belgium. Further in-depth studies are necessary to unravel the role of these species as abortifacient agents in cattle and to include them in bovine abortion monitoring programmes.

Equine abortion, stillbirth and neonatal death cause major economic losses to the equine industry worldwide. Both non-infectious and a wide range of infectious causes have been described. However, the relative contribution of pathogens to equine abortion, stillbirth and neonatal death is poorly documented, since available studies involve only a limited number of pathogens. Therefore, the objectives of the present retrospective monitoring study were to determine the prevalence of infectious agents associated with equine abortion and perinatal mortality in Belgium, and to set up a protocol usable under field conditions using polymerase chain reaction targeting. A real-time simple polymerase chain reaction for eight different abortifacient pathogens was conducted leading to the detection of at least one infectious agent in 37% of 105 analyzed cases. In the diagnosed cases, equine herpesvirus-1 was the most detected pathogen (49%), followed by Streptococcus equi subspecies zooepidemicus (28%), Coxiella burnetii (18%), Leptospira interrogans (3%) and Neospora caninum (3%). None of the analyzed cases was positive for equine viral arteritis, equine herpesvirus-4 and Chlamydophila spp. In this study, PCR targeting is shown to have its value to detect a (co)-infectious cause in equine abortion, stillbirth and neonatal death, especially in field conditions where autolysis and contamination might preclude a full post-mortem examination protocol based on classical microbiological examination.

BACKGROUND:Anaplasma phagocytophilum is a tick-borne zoonotic bacterium that is the aetiologic pathogen of tick-borne fever (TBF) in ruminants. In clinical bovine cases of TBF, abortion and stillbirth may be observed. However, in this regard, the pathophysiology of TBF has not yet been completely elucidated, and no clear guidelines to diagnose A. phagocytophilum-related abortions and perinatal mortalities (APM) are available.METHODS:This exploratory study aimed to investigate the presence of A. phagocytophilum in bovine cases of APM and determine whether placental or fetal spleen tissue has the greatest sensitivity for A. phagocytophilum identification. The placenta and fetal spleen of 150 late-term bovine APM cases were analysed using real-time PCR to detect A. phagocytophilum.RESULTS:A total of 2.7% of sampled placentas were positive for A. phagocytophilum, while none of the fetal spleen samples was.LIMITATIONS:No histopathology to detect associated lesions was performed. Consequently, no evidence of causality between the detection of A. phagocytophilum and APM events could be achieved.CONCLUSION:The detection of A. phagocytophilum suggests a potential role of this pathogen in bovine APM, and placental tissue seems to be the most suitable tissue for its identification.

Neospora caninum is a protozoan parasite that causes abortion, perinatal mortality, and subfertility in cattle worldwide. Despite the presence of the DNA of the parasite in semen of infected bulls, the effect on semen quality has not been extensively studied. This study aimed to investigate the effect of a natural Neospora caninum infection on fresh and frozen semen quality parameters in Belgian Blue bulls. Two hundred and fourteen bulls were serologically screened with an indirect ELISA-test specific for anti-Neospora caninum antibodies, every two months during one year. In addition to serological screening, semen was collected twice weekly using an artificial vagina. The following semen quality parameters were assessed: ejaculate volume, concentration, total motility of fresh semen samples, as well as morphology, total and progressive motility for frozen/thawed semen samples. Bulls were semen sampled throughout the whole year, but only semen samples of bulls that had six consecutive positive or negative ELISA-test results were included in our dataset (n 1/4 98). Generalized linear and binomial mixed models were used for statistical analysis of each outcome variable. In these models the explanatory variables were defined as: age, barn location, mean Temperature Humidity Index (THI) during sperm production (14-42 days before sampling), maximum daily THI at collection, season of sperm production, season at collection and the Neospora caninum antibody test results. Initially, individual explanatory variables were tested in univariable models for each outcome variable. Akaike information criterion (AIC) values were used to select explanatory variables to build a multivariable model, where the Neospora caninum test result was forced in all models. The present study reveals an overall apparent seroprevalence of Neospora caninum of 9,2% in the study population. No significant associations were detected between natural neosporosis, substantiated by ELISA-antibody levels, and any of our tested outcome variables on fresh and frozen/thawed semen samples. Based on the results of the present study, we conclude that Neospora caninum seropositive bulls do not have lower semen quality parameters compared with seronegative bulls. (c) 2022 Elsevier Inc. All rights reserved.

Abortion and perinatal mortality, leading causes of economic loss in cattle industry, are the consequence of both non-infectious and a wide range of infectious causes. However, the relative contribution of pathogens to bovine abortion and perinatal mortality is poorly documented, since available studies involved only a limited number of pathogens. Therefore, the objectives of the present monitoring study were to determine the prevalence of infectious agents associated with bovine abortion and perinatal mortality, and to identify differences in production type, gestation length, parity and seasonality by using mixed effect models (logistic regression). A pre-established sampling protocol based on the collection of the aborted fetus/calf and a corresponding maternal blood sample, involving diagnostic testing for 10 pathogens, was performed. At least one potential causal agent of the abortion or perinatal mortality was detected in 39 % of cases. In these diagnosed cases, Neospora caninum was the most detected pathogen, followed by Trueperella pyogenes, BVDv, Escherichia coli, and Aspergillus fumigatus. Neospora caninum [odds ratio (OR): 0.4; 95 % confidence interval (CI): 0.3-0.7] and Aspergillus fumigatus (OR: 0.1; 95 % CI: 0.1-0.3) were detected less in late versus early gestation. Aspergillus fumigatus was less common in dairy in comparison to beef abortion cases (OR: 0.2; 95 % CI: 0.1-0.6). Winter was associated with a lower positivity for Neospora caninum and BVDv in comparison to warmer seasons. Despite extensive diagnostic testing, an etiological diagnosis was not reached in 61 % of cases, highlighting the need for even more extensive (non-)infectious disease testing or more accurate tests.

In deze veldstudie uitgevoerd in de Vlaamse melkveehouderij wordt aangetoond dat factoren, zoals lactatiestadium, bedrijfstype (met of zonder weidegang) en seizoen, geassocieerd zijn met plasma- β-caroteen (bC) en vitamine E (VitE)-concentraties bij melkvee. De iCheck bC is een eenvoudig apparaat waarmee de bC-status van een koe snel en op het bedrijf geëvalueerd kan worden. Een derde van de melkkoeien vertoonde deficiënties in plasma-bC en VitE en dit voornamelijk tijdens de vroege lactatie en op bedrijven zonder weidegang. De opname van vers gras kon de daling in plasma-bC en VitE vroeg na de kalving niet opheffen. De bC- en VitE-status van droogstaande koeien was significant beter bij deze met mogelijkheid tot weidegang. Deze bevindingen kunnen bijdragen tot het herformuleren van de diëtaire antioxidant-aanbevelingen met als doel hoogproductieve melkkoeien in optimale gezondheid te houden.

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.

Mycoplasma bovis is a highly contagious bacterium, which predominantly causes chronic pneumonia, otitis and arthritis in calves and mastitis in adult cattle. In humans, Mycoplasma species have been associated with post-surgical infections. The present study aimed to identify the bacteria associated with three outbreaks of infected seromas after caesarian section in Belgian Blue beef cattle. A total of 10 cases occurred in three herds which were in close proximity of each other and shared the same veterinary practice. M. bovis could be cultured from seroma fluid in five of the six referred animals, mostly in pure culture and was isolated from multiple chronic sites of infection (arthritis and mastitis) as well. DNA fingerprinting of the isolates targeting two insertion sequence elements suggested spread of M. bovis from chronic sites of infection (udder and joints) to the postsurgical seromas. Identical genetic profiles were demonstrated in two animals from two separate farms, suggesting spread between farms. Mortality rate in the referred animals positive for M. bovis in a seroma was 80% (4/5), despite intensive treatment. A massive increase in antimicrobial use was observed in every affected farm. These observations demonstrate involvement of mycoplasmas in outbreaks of postsurgical seromas in cattle.

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.

Veterinary RecordVolume 175, Issue 22 p. 562-562 Research Detection of Chlamydia psittaci in Belgian cattle with signs of respiratory disease and milk drop syndrome H. Van Loo DVM, Corresponding Author H. Van Loo DVM hans.vanloo@dgz.be Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumE-mail for correspondence: hans.vanloo@dgz.beSearch for more papers by this authorB. Pardon DVM, Ph.D, B. Pardon DVM, Ph.D Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorP. De Schutter DVM, P. De Schutter DVM Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorK. De Bleecker DVM, K. De Bleecker DVM Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumSearch for more papers by this authorD. Vanrompay DVM, Ph.D, D. Vanrompay DVM, Ph.D Department of Molecular Biotechnology, Ghent University, Coupure links 653, Ghent, 9000 BelgiumSearch for more papers by this authorP. Deprez DVM, Ph.D, Dipl. ECBHM, P. Deprez DVM, Ph.D, Dipl. ECBHM Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorJ. Maris DVM, J. Maris DVM Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumSearch for more papers by this author H. Van Loo DVM, Corresponding Author H. Van Loo DVM hans.vanloo@dgz.be Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumE-mail for correspondence: hans.vanloo@dgz.beSearch for more papers by this authorB. Pardon DVM, Ph.D, B. Pardon DVM, Ph.D Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorP. De Schutter DVM, P. De Schutter DVM Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorK. De Bleecker DVM, K. De Bleecker DVM Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumSearch for more papers by this authorD. Vanrompay DVM, Ph.D, D. Vanrompay DVM, Ph.D Department of Molecular Biotechnology, Ghent University, Coupure links 653, Ghent, 9000 BelgiumSearch for more papers by this authorP. Deprez DVM, Ph.D, Dipl. ECBHM, P. Deprez DVM, Ph.D, Dipl. ECBHM Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820 BelgiumSearch for more papers by this authorJ. Maris DVM, J. Maris DVM Animal Health Center Flanders (DGZ Vlaanderen), Industrielaan 29, Torhout, 8820 BelgiumSearch for more papers by this author First published: 06 December 2014 https://doi.org/10.1136/vr.102527Citations: 1 Provenance: not commissioned; externally peer reviewed Read the full textAboutRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume175, Issue22December 2014Pages 562-562 RelatedInformation RecommendedPrevalence of antibodies to bovine viral diarrhoea virus in bulk tank milk and associated risk factors in Scottish dairy herdsR. W. Humphry BA, PhD, Dip. Stat., F. Brülisauer Dr. Med. Vet., Dipl. ECVPH, MRCVS, I. J. McKendrick BSc (Hons), PhD, P. F. Nettleton BVMS, MSc, PhD, MRCVS, G. J. Gunn BVMS, MSc, Dipl ECVPH, Dipl ECBHM, RCVS Spec. Vet. Epi., MRCVS, Veterinary RecordIsolation of Mycoplasma species from the lower respiratory tract of healthy cattle and cattle with respiratory disease in BelgiumA. Thomas DVM, I. Dizier, A. Trolin, J. Mainil DVM, PhD, A. Linden DVM, PhD, H. Ball DVM, PhD, FRCPath, C. Bell, Veterinary RecordProspective cohort study to assess rates of contagious disease in pre‐weaned UK dairy heifers: management practices, passive transfer of immunity and associated calf healthKate F Johnson, Natalie Chancellor, Charlotte C Burn, D Claire Wathes, Veterinary Record OpenPrevalence of individual and bulk tank milk antibodies of bovine herpesvirus type 1 and its relation to milk quality parameters on dairy farms in Catalonia (north‐east Spain)Ramon Armengol, Daniel Villalba, Ester Coma, Lourdes Porquet, Anna Jubert, Carmina Nogareda, Veterinary Record Open

Recently, sharp increases in the prevalence of rumen fluke infections have been recorded throughout Western Europe. However, scarce information is available on the diagnosis, pathogenic importance and control of this parasite. We undertook 3 pilot studies to gain more insights into these aspects of rumen fluke biology in cattle. First, we evaluated the diagnostic performance of mini-FLOTAC to detect adult rumen fluke infections based on faecal egg count in an abattoir survey and found high sensitivity (0.94) and specificity (0.98). Moreover, there was an association between ruminal fluke burden (assessed by visual scoring) and faecal egg count and a cut-off of 200 eggs per gram is proposed to detect highly infected animals (>200 flukes present in the rumen and/or reticulum). There was also a significant association between ruminal fluke burden and faecal consistency. However, in a second study, we performed a case-control field survey to investigate the association between rumen fluke infection and herd-level problems with diarrhoea and no association was found. Finally, we evaluated the use of closantel (Flukiver®, Elanco Animal Health, subcutaneous administration at 10 mg/kg) to treat rumen fluke infection on 3 herds, but no significant reduction in egg output post-treatment was found. Because this result is in contrast with a previous study using an oral dose of closantel, more research is required into the effect of administration route on the efficacy of closantel on rumen fluke.

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.

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 11635 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: 98.3499.97) and within-herd seroprevalence at 86.3% (95% CI: 84.7587.71). 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: 61.3468.3) estimated for the 612months of age, 86.79% (95% CI: 84.4388.85) for the 1224months of age and 94.4% (95% CI: 93.1495.44) for the animals older than 24months. 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.

After a short winter break, bluetongue virus serotype 8 was responsible in 2007 for a large-scale epidemic among ruminant populations in Western Europe. Little is known about the mechanisms allowing the virus to survive winter conditions. A yearly mass vaccination of cattle and sheep started in spring 2008, which was recognized as successful in terms of clinical protection, but occult circulation of the bluetongue virus has not been adequately addressed. We studied the carriage of bluetongue RNA in the spleen of cattle in the vector-free period and the circulation of bluetongue virus in cattle populations in Belgium since the introduction of vaccination programmes. Overall, the results presented here show evidence for the long-term carriage of bluetongue virus RNA in the spleen of cattle and demonstrated a low but significant circulation and transplacental transmission of bluetongue virus in Belgian cattle in 2009, with apparent disappearance in 2010.

SAMENVATTING Een 8 maanden drachtige Belgisch witblauwe (BWB) vaars werd voor onderzoek aangeboden vanwege een abnormaal vergroot buikvolume. Een hydrops uteri werd gediagnosticeerd en de partus werd geinduceerd. Bij het kalf, dat via een keizersnede werd geboren, was op de onderkaak een grote roodgekleurde zwelling aanwezig. De lijkschouwing en het histologisch onderzoek toonden aan dat het een vasculair hamartoma betrof.

An 8 months pregnant Belgian blue heifer was presented because of an excessive swelling of the abdomen. Clinical examination revealed that the heifer was suffering from a hydrops uteri and parturition was induced. The calf, born by caesarean section, had a big red colored mass on its mandible. Necropsy and histology identified the swelling as a vascular hamartoma.