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impact of human interventions on the spread of bluetongue virus serotype 8 during the 2006 epidemic in north-western europe.bluetongue virus (btv) can be spread by movement or migration of infected ruminants. infected midges (culicoides sp.) can be dispersed with livestock or on the wind. transmissions of infection from host to host by semen and trans-placental infection of the embryo from the dam have been found. as for any infectious animal disease, the spread of btv can be heavily influenced by human interventions preventing or facilitating the transmission pathways. this paper describes the results of investigati ...200818649960
a cross-sectional study to determine the seroprevalence of bluetongue virus serotype 8 in sheep and goats in 2006 and 2007 in the netherlands.in august 2006 a major epidemic of bluetongue virus serotype 8 (btv8) started off in north-west europe. in the course of 2007 it became evident that btv8 had survived the winter in north-west europe, re-emerged and spread exponentially. recently, the european union decided to start vaccination against btv8. in order to improve the understanding of the epidemiological situation, it was necessary to execute a cross-sectional serological study at the end of the bt vector season. cattle were the tar ...200818752681
[bluetongue virus serotype 8 in healthy young calves].following the detection in northern ireland of bluetongue serotype-8 (btv-8) pcr-positive calves born from pcr-negative but seropositive heifers imported from the netherlands, an investigation was started to determine whether pcr-positive calves were born in the first quarter of 2008 in the netherlands. blood samples were collected on 43 dairy farms from 388 cow-calf combinations. all calves were at least 10-days-old and had been born after 1 january 2008. in total, 229 cows had had a btv-8 infe ...200819133436
[bluetongue disease in swiss sheep breeds: clinical signs after experimental infection with bluetongue virus serotype 8].clinical disease of bluetongue (bt) in sheep may differ depending on breed, age and immunity of infected sheep and may also vary between serotype and strain of bt virus (btv). since there are no data available on the susceptibility of swiss sheep breeds for bt, we performed experimental infection of the 4 most common swiss sheep breeds and the highly susceptible poll dorset sheep with the btv serotype 8 (btv-8) circulating in northern europe since 2006. clinical signs were assessed regarding sev ...200818821508
[vaccination against bluetongue: safety and immune response in the field].bluetongue, caused by the bluetongue virus serotype 8 has rapidly spread through europe since 2006. the first cases in switzerland were detected in october 2007. the european union and switzerland launched a vaccination campaign in june 2008. this study aims to demonstrate the safety and the immune response of the three vaccines used in switzerland under practical conditions in the field. the trial was carried out in cattle, sheep and goats. based on the results of this study recommendations for ...200919263379
evidence for transplacental transmission of the current wild-type strain of bluetongue virus serotype 8 in cattle. 200818621997
clinical signs and pathology shown by british sheep and cattle infected with bluetongue virus serotype 8 derived from the 2006 outbreak in northern europe.four poll dorset sheep and four holstein-friesian cattle were infected with the northern european strain of bluetongue virus (btv), btv-8, to assess its pathogenicity in uk breeds. the time course of infection was monitored in both species by using real-time reverse transcriptase-pcr (rt-pcr), conventional rt-pcr and serology. two of the sheep developed severe clinical signs that would have been fatal in the field; the other two were moderately and mildly ill, respectively. the cattle were clini ...200717720961
efficacy of three inactivated vaccines against bluetongue virus serotype 8 in sheep.bluetongue has become a major animal health issue in the european union. the member states and switzerland have agreed on a vaccination strategy. three different inactivated monovalent vaccines against bluetongue virus serotype 8 were selected for the compulsory vaccination program carried out in germany in 2008. the efficacy of these vaccines was evaluated in a pilot study in sheep immunised under field conditions by clinical, virological and serological examination before and after experimenta ...200919406189
experimental transplacental infection of sheep with bluetongue virus serotype 8. 200919377090
epidemiology of bluetongue virus serotype 8, germany.in germany, bluetongue disease had not been reported before 2006. during august 2006-august 2008, >24,000 bluetongue virus serotype 8 infections were reported, most (20,635) in 2007. in 2006 and 2007, respectively, case-fatality rates were 6.4% and 13.1% for cattle and 37.5% and 41.5% for sheep. vaccination in 2008 decreased cases.200919239757
establishing a cost-effective national surveillance system for bluetongue using scenario tree modelling.vector-borne diseases pose a special challenge to veterinary authorities due to complex and time-consuming surveillance programs taking into account vector habitat. using stochastic scenario tree modelling, each possible surveillance activity of a future surveillance system can be evaluated with regard to its sensitivity and the expected cost. the overall sensitivity of various potential surveillance systems, composed of different combinations of surveillance activities, is calculated and the pr ...200919607784
use of inactivated bluetongue virus serotype 8 vaccine against virulent challenge in sheep and cattle.the immunisation properties of an inactivated bluetongue virus serotype 8 (btv-8) vaccine were evaluated in sheep and cattle. five sheep were vaccinated with one dose of vaccine and five cattle were vaccinated with two doses 28 days apart. six sheep and five cattle served as unvaccinated controls. all animals were subjected to a virulent btv-8 challenge, and safety and antibody responses were monitored. all control animals developed disease and viraemia, while vaccinated animals were clinically ...200919783850
monitoring of putative vectors of bluetongue virus serotype 8, germany.to identify the vectors of bluetongue virus (btv) in germany, we monitored culicoides spp. biting midges during april 2007-may 2008. molecular characterization of batches of midges that tested positive for btv suggests c. obsoletus sensu stricto as a relevant vector of bluetongue disease in central europe.200919788820
epizootic congenital hydranencephaly and abortion in cattle due to bluetongue virus serotype 8 in the netherlands.an outbreak of hydranencephaly in aborted foetuses and newborn calves occurred following the 2007 epidemic of bluetongue serotype 8 (btv8\net2006) in the netherlands. in total 35 aborted foetuses and 20 live-born calves, submitted from september 2007 to may 2008, were examined pathologically. foetuses with gestational ages between 4 and 9 months (mean 6.8 month) showed varying stages of cerebral malformation. initial stages were cavitations in the cerebral hemispheres with massive destruction of ...200919522347
seroconversion, neutralising antibodies and protection in bluetongue serotype 8 vaccinated sheep.bluetongue virus serotype 8 (btv-8) has caused a major outbreak of disease in cattle and sheep in several countries across northern and western europe from 2006 to 2008. in 2008 the european union instigated a mass-vaccination programme in affected countries using whole virus inactivated vaccines. we evaluated vaccinal responses in sheep and the ability of the vaccine to protect against experimental challenge. sheep vaccinated 10 months previously under field conditions were challenged with btv- ...200919786141
neutralising antibody responses in cattle and sheep following booster vaccination with two commercial inactivated bluetongue virus serotype 8 vaccines.cattle and sheep that had received a primary course of vaccination with an inactivated bluetongue virus serotype 8 (btv-8) vaccine were booster vaccinated 6 or 12 months later with the homologous vaccine or an alternative inactivated btv-8 vaccine and neutralising antibody responses were determined. antibody titres to the alternative vaccine were significantly higher than to the homologous vaccine (p=0.013) in cattle. there was no significant difference between the antibody responses to alternat ...201120466568
epidemiologic characteristics of bluetongue virus serotype 8 laboratory-confirmed outbreaks in the netherlands in 2007 and a comparison with the situation in 2006.a major epidemic of bluetongue virus serotype 8 (btv-8) occurred in western europe in 2006. during 2007 it became evident that btv-8 had survived the winter and a re-emerging epidemic quickly developed. the objective of this study was to describe the severity and clinical impact of the btv-8 epidemic in 2007 in the netherlands in laboratory-confirmed outbreaks and to compare this with the situation in 2006. the relative frequency of clinical signs in btv-8 affected sheep flocks and cattle herds ...200919740560
virological and pathological findings in bluetongue virus serotype 8 infected sheep.twenty-seven sheep of the four most common swiss breeds and the english breed poll dorset were experimentally infected with a northern european field strain of bluetongue virus serotype 8 (btv-8). animals of all breeds developed clinical signs, viremia and pathological lesions, demonstrating that btv-8 is fully capable of replicating and inducing bluetongue disease (bt) in the investigated sheep. necropsy performed between 10 and 16 days post-infectionem (d.p.i.) revealed bt-typical hemorrhages, ...201020153937
the impact of naturally-occurring, trans-placental bluetongue virus serotype-8 infection on reproductive performance in sheep.infection with bluetongue virus serotype (btv)-8 occurred in ruminants in 2006 in central-western europe. the trans-placental passage of this virus has been demonstrated in naturally- and experimentally-infected cattle and in experimentally-infected sheep. trans-placental transmission is potentially important in the 'over-wintering' of this virus and its subsequent impact on reproductive performance. this epidemiological study was carried out on a sheep flock in belgium that had experienced a se ...201120061168
bluetongue virus in wild deer, belgium, 2005-2008.to investigate bluetongue virus serotype 8 infection in belgium, we conducted a virologic and serologic survey on 2,416 free-ranging cervids during 2005-2008. infection emerged in 2006 and spread over the study area in red deer, but not in roe deer.201020409376
questionnaire survey about the motives of commercial livestock farmers and hobby holders to vaccinate their animals against bluetongue virus serotype 8 in 2008-2009 in the netherlands.after a massive epidemic of bluetongue virus serotype 8 (btv-8) among ruminants in 2006-2007 in the european union (eu), the netherlands started a voluntary emergency vaccination campaign in may 2008, subsidized by the eu. at the start of a new campaign in 2009, without subsidized vaccination, we investigated by mail survey the motives of farmers and hobby holders to vaccinate against btv-8 in 2008 and 2009. mean vaccine uptake in 2008 was: 73% in sheep, 71% in cattle, 43% in goat farms and 67% ...201020123141
financial evaluation of different vaccination strategies for controlling the bluetongue virus serotype 8 epidemic in the netherlands in 2008.bluetongue (bt) is a vector-borne disease of ruminants caused by bluetongue virus that is transmitted by biting midges (culicoides spp.). in 2006, the introduction of btv serotype 8 (btv-8) caused a severe epidemic in western and central europe. the principal effective veterinary measure in response to bt was believed to be vaccination accompanied by other measures such as movement restrictions and surveillance. as the number of vaccine doses available at the start of the vaccination campaign wa ...201121573195
the spread of bluetongue virus serotype 8 in great britain and its control by vaccination.bluetongue (bt) is a viral disease of ruminants transmitted by culicoides biting midges and has the ability to spread rapidly over large distances. in the summer of 2006, btv serotype 8 (btv-8) emerged for the first time in northern europe, resulting in over 2000 infected farms by the end of the year. the virus subsequently overwintered and has since spread across much of europe, causing tens of thousands of livestock deaths. in august 2007, btv-8 reached great britain (gb), threatening the larg ...201020179768
colostral antibody protection and interference with immunity in lambs born from sheep vaccinated with an inactivated bluetongue serotype 8 vaccine.widespread vaccination programmes against bluetongue virus serotype 8 (btv-8), using inactivated vaccines, are being carried out across many countries in northern, western and southern europe. this study investigates the extent and length of colostral antibody protection, as well as the degree of colostral antibody induced interference of the immune response to btv-8, in sheep. significantly lower titres of neutralising antibodies were transferred in colostrum to lambs born from sheep vaccinated ...201020123052
transplacental transmission of bluetongue virus serotype 8 in ewes in early and mid gestation.the ability of bluetongue virus serotype 8 (btv-8) originating from the 2006 european outbreak to cross the ovine placenta during early and mid gestation was investigated in two separate experiments. in the first experiment, 16 ewes were infected with btv-8 at 70-75 days gestation. the foetuses were collected at 18-19 days after infection (dpi). btv-8 could be isolated from at least two organs of 19 out of 40 lambs and from 11 out of 16 infected ewes. in the second experiment, 20 btv-8 infected ...201021145670
anatomy of bluetongue virus serotype 8 epizootic wave, france, 2007-2008.the introduction of bluetongue virus serotype 8 into northern europe at the end of summer 2006 initiated one of the most widespread epizootics of bluetongue infection ever to occur. in winter 2007-2008, a cross-sectional serologic study was conducted in france along a transect perpendicular to the epizootic wave. cattle herd-level seroprevalence varied from 4% to 100%, and animal-level seroprevalence from <1% to 40%. only a low proportion of seropositive herds reported clinical cases in 2007. sh ...201021122214
comparative safety study of three inactivated btv-8 vaccines in sheep and cattle under field conditions.after massive epidemics of bluetongue disease in 2006 and 2007, germany has started a compulsory vaccination program against bluetongue virus serotype 8 (btv-8). since the available vaccines had not yet been registered and only limited data were available on their performance, a safety study was conducted with three different inactivated monovalent vaccines under consideration for use in germany. a total of 1007 sheep and 893 cattle were vaccinated and subsequently compared with 638 control anim ...200919410620
experimental oral infection of bluetongue virus serotype 8 in type i interferon receptor-deficient mice.the identification of transmission routes for bluetongue virus (btv) is essential to improve the control of the disease. although btv is primarily transmitted by several species of culicoides biting midges, there has been evidence of transplacental and oral transmission. we now report that ifnar((-/-)) mice are susceptible to oral infection by btv-8. viraemia, clinical manifestations and tissue lesions are similar to those in intravenously infected mice. in addition, we show that the oral cavity ...201020719994
the presence of bluetongue virus serotype 8 rna in belgian cattle since 2008.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 ...201121605347
bluetongue virus rna detection by rt-qpcr in blood samples of sheep vaccinated with a commercially available inactivated btv-8 vaccine.in 2008, a country-wide bluetongue virus 8 (btv-8) vaccination campaign has been initiated in austria, using a single commercial inactivated btv-8 vaccine. based on preliminary data, we hypothesised that vaccine-derived btv rna is transiently detectable by reverse transcription quantitative real-time pcr (rt-qpcr) in the blood of vaccinated animals. thus btv-8 vaccine was administered to five btv-naïve adult sheep and blood samples were taken at various time-points post-vaccination. btv rna was ...201020600511
modelling local dispersal of bluetongue virus serotype 8 using random walk.the knowledge of the place where a disease is first introduced and from where it later spreads is a key element for the understanding of an epizootic. for a contagious disease, the main method is back tracing. for a vector-borne disease such as the bluetongue virus serotype 8 epizootic that occurred in 2006 in north-western europe, the efficiency of tracing is limited because many infected animals are not showing clinical signs. in the present study, we propose to use a statistical approach, ran ...200818640733
performance of clinical signs to detect bluetongue virus serotype 8 outbreaks in cattle and sheep during the 2006-epidemic in the netherlands.the performance of clinical signs as a diagnostic test for the detection of btv-8 outbreaks during the 2006-epidemic in the netherlands was evaluated by constructing and analysing receiver operating characteristic (roc) curves. the area under the roc curve of the bt-associated clinical signs in cattle was 0.77. an optimal efficient test (maximising both sensitivity and specificity) in cattle herds combined a sensitivity (se) of 67% with a specificity (sp) of 72%, comprising the following clinica ...200818164148
evidence for transplacental and contact transmission of bluetongue virus in cattle.this paper presents evidence that a field strain of bluetongue virus serotype 8 (btv-8) was transmitted transplacentally and that it was also spread by a direct contact route. twenty pregnant heifers were imported from the netherlands into northern ireland during the midge-free season. tests before and after the animals were imported showed that eight of them had antibodies to bluetongue virus, but no viral rna was detected in any of them by reverse transcriptase-pcr (rt-pcr). two of the seropos ...200818708653
bluetongue virus serotype 8 in the ardennes in 2007. 200819043098
evaluation of antibody-elisa and real-time rt-pcr for the diagnosis and profiling of bluetongue virus serotype 8 during the epidemic in belgium in 2006.in 2006 bluetongue (bt) emerged for the first time in north-western europe. reliable diagnostic tools are essential in controlling bt but data on the diagnostic sensitivity (se) and specificity (sp) are often missing. this paper aims to describe and analyse the results obtained with the diagnostics used in belgium during the 2006 bt crisis. the diagnosis was based on a combination of antibody detection (competitive elisa, celisa) and viral rna detection by real-time rt-pcr (rt-qpcr). the perform ...200818093753
bluetongue virus serotype 8-associated congenital hydranencephaly in calves.hydranencephaly, the almost complete absence of the cerebral parenchyma, induced by infection with modified live bluetongue virus (btv) crossing the placenta has previously been reported in sheep and rarely in cattle in the usa and in south africa. the current study describes 29 cases of hydranencephaly in bovine foetuses and 'dummy' calves up to 3 months of age in belgium associated with natural btv serotype 8 infection very early in gestation. histological examination of the remaining cerebral ...200818503510
evaluation of humoral response and protective efficacy of three inactivated vaccines against bluetongue virus serotype 8 one year after vaccination of sheep and cattle.the long-term efficacy of three commercially available inactivated vaccines against bluetongue virus serotype 8 (btv-8) (bluevac) 8, zulvac 8, and btvpur alsap 8) was evaluated in a seroprevalence study and challenge experiments. seroprevalences 1 year after vaccination ranged from 75% to 100%. in two infection experiments, groups of vaccinated sheep and cattle selected either randomly or for low antibody levels were challenged with a european btv-8 strain 12 months after vaccination. with two e ...201020438878
Clinical disease in sheep caused by bluetongue virus serotype 8, and prevention by an inactivated vaccine.The ability to reduce clinical signs, induce neutralizing antibodies, and perhaps most importantly, to prevent or reduce viraemia (and therefore virus-transmission), represent primary criteria for assessment of bluetongue virus (BTV) vaccine efficacy. Identification of BTV challenge-strains that reliably induce viraemia and clinical signs comparable to those in naturally infected animals, is therefore important for vaccine evaluation. Texel cross-breed and Dorset Poll sheep vaccinated with inact ...201122207091
possible routes of introduction of bluetongue virus serotype 8 into the epicentre of the 2006 epidemic in north-western europe.in august 2006, bluetongue (bt) was notified in the netherlands on several animal holdings. this was the onset of a rapidly spreading bt-epidemic in north-western europe (latitude >51 degrees n) that affected cattle and sheep holdings in the netherlands, belgium, germany, france and luxembourg. the outbreaks were caused by bluetongue virus (btv) serotype 8, which had not been identified in the european union before. bluetongue virus can be introduced into a free area by movement of infected rumi ...200818667252
[epidemiology of bluetongue virus serotype 8 outbreaks in the netherlands in 2006].in august 2006 a major epidemic of bluetongue (bt) occurred in north-western europe, affecting the netherlands, belgium, germany, luxemburg, and the north of france. it was caused by br virus serotype 8 (btv-8), a serotype previously unknown to the eu. although clinical disease is usually restricted to sheep, this virus also caused clinical disease in a small proportion of cattle. the last clinical outbreak of bt in the netherlands occurred mid-december 2006. the delay between observation of the ...200818429403
Effect of vaccination with an inactivated vaccine on transplacental transmission of BTV-8 in mid term pregnant ewes and heifers.The effect of vaccination with a commercial inactivated Bluetongue virus serotype 8 (BTV-8) vaccine on the ability of BTV-8 to cross the ruminant placenta was investigated in two experiments. Ten pregnant ewes (Experiment 1) or heifers (Experiment 2) were vaccinated according to the manufacturer's instructions. Three weeks after the completion of the vaccination schedule, all vaccinated animals were infected with BTV-8 together with ten non-vaccinated pregnant animals that served as challenged c ...201222107846
clinical signs of bluetongue virus serotype 8 infection in sheep and goats. 200717965371
assessing the consequences of an incursion of a vector-borne disease i. identifying feasible incursion scenarios for bluetongue in scotland.following the arrival of bluetongue virus serotype 8 (btv-8) in southeast england in september 2007, the scottish government commissioned research to assess the economic consequences of a btv-8 incursion to scotland. here we present the first component of the assessment, which entailed identifying feasible incursion scenarios for the virus. our analyses focused on three routes of introduction: wind-borne dispersal of infected vectors, import of infected animals and northwards spread of btv from ...201021352785
bluetongue serotype 8 vaccine coverage in northern and south-eastern england in 2008.a postal survey of all registered cattle and sheep farmers in east anglia was carried out from july 2008 to determine bluetongue virus serotype 8 (btv-8) vaccine uptake in the region. the vaccine was available to farmers in this region from may 2008. the survey was repeated in cumbria and northumberland at the beginning of 2009. in these regions, the vaccine was not available until september 1, 2008. holding-level vaccine uptake was estimated to be 85 per cent (95 per cent confidence interval [c ...201121493449
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