Bluetongue in Belgium: Episode II

Meroc, Estelle; Herr, Cécile; Verheyden, Bart; Hooyberghs, J.; Houdart, P.; Raemaekers, M.; Vandenbussche, Frank; Clercq, Kris De; Mintiens, Koen

doi:10.1111/j.1865-1682.2008.01063.x

Cited by 29 publications

(20 citation statements)

References 12 publications

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“…BTV-8 NET2006 is considered to be a highly pathogenic virus (both in terms of morbidity and mortality) and the cause of one of the largest outbreaks of bluetongue in history (48–51). However, in our experimental setting, we did not find any difference in virulence between BTV-8 NET2006 and another serotype, such as BTV-2 IT2000 , which was isolated in Italy in the year 2000 from a naturally occurring case of bluetongue in sheep.…”

Section: Discussionmentioning

confidence: 99%

“…For example, the North European BTV-8 strains that spread since 2006 in Northern Europe is considered highly virulent, as it induced high levels of mortality in naive sheep and in some cases also caused severe clinical disease in cattle (48–51). On the other hand, it is interesting to note that no clinical cases of disease were observed even in sheep when BTV-8 reached Northern Italy and Sardinia a few years later (G. Savini, personal communication).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Virus and Host Factors Affecting the Clinical Outcome of Bluetongue Virus Infection

Caporale

Gialleonorado

Janowicz

et al. 2014

J Virol

103

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Bluetongue is a major infectious disease of ruminants caused by bluetongue virus (BTV), an arbovirus transmitted by Culicoides. Here, we assessed virus and host factors influencing the clinical outcome of BTV infection using a single experimental framework. We investigated how mammalian host species, breed, age, BTV serotypes, and strains within a serotype affect the clinical course of bluetongue. Results obtained indicate that in small ruminants, there is a marked difference in the susceptibility to clinical disease induced by BTV at the host species level but less so at the breed level. No major differences in virulence were found between divergent serotypes (BTV-8 and BTV-2). However, we observed striking differences in virulence between closely related strains of the same serotype collected toward the beginning and the end of the European BTV-8 outbreak. As observed previously, differences in disease severity were also observed when animals were infected with either blood from a BTV-infected animal or from the same virus isolated in cell culture. Interestingly, with the exception of two silent mutations, full viral genome sequencing showed identical consensus sequences of the virus before and after cell culture isolation. However, deep sequencing analysis revealed a marked decrease in the genetic diversity of the viral population after passaging in mammalian cells. In contrast, passaging in Culicoides cells increased the overall number of low-frequency variants compared to virus never passaged in cell culture. Thus, Culicoides might be a source of new viral variants, and viral population diversity can be another factor influencing BTV virulence.IMPORTANCE Bluetongue is one of the major infectious diseases of ruminants. It is caused by an arbovirus known as bluetongue virus (BTV). The clinical outcome of BTV infection is extremely variable. We show that there are clear links between the severity of bluetongue and the mammalian host species infected, while at the breed level differences were less evident. No differences were observed in the virulence of two different BTV serotypes (BTV-8 and BTV-2). In contrast, we show that the European BTV-8 strain isolated at the beginning of the bluetongue outbreak in 2006 was more virulent than a strain isolated toward the end of the outbreak. In addition, we show that there is a link between the variability of the BTV population as a whole and virulence, and our data also suggest that Culicoides cells might function as an “incubator” of viral variants.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Virus and Host Factors Affecting the Clinical Outcome of Bluetongue Virus Infection

Caporale

Gialleonorado

Janowicz

et al. 2014

J Virol

103

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“…It was suggested that the winter season of 2006/2007 would halt the BTV epidemic, assuming that the chain of transmission would be broken by a stop in the life cycle of the vector because of low temperatures. However, during 2007 it became evident that BTV-8 had survived the winter in Western Europe and a re-emerging epidemic quickly developed within the originally affected countries, affecting approximately 40 000 locations with ruminants [5-7]. In addition, BTV-8 was introduced into the United Kingdom, Denmark, Switzerland and the Czech Republic.…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis of transmission parameters for bluetongue virus serotype 8 in Western Europe in 2006

Koeijer

Boender

Nodelijk

et al. 2011

Vet Res

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The recent bluetongue virus serotype 8 (BTV-8) epidemic in Western Europe struck hard. Controlling the infection was difficult and a good and safe vaccine was not available until the spring of 2008. Little was known regarding BTV transmission in Western Europe or the efficacy of control measures. Quantitative details on transmission are essential to assess the potential and efficacy of such measures.To quantify virus transmission between herds, a temporal and a spatio-temporal analysis were applied to data on reported infected herds in 2006. We calculated the basic reproduction number between herds (Rh: expected number of new infections, generated by one initial infected herd in a susceptible environment). It was found to be of the same order of magnitude as that of an infection with Foot and Mouth Disease (FMD) in The Netherlands, e.g. around 4. We concluded that an average day temperature of at least 15°C is required for BTV-8 transmission between herds in Western Europe. A few degrees increase in temperature is found to lead to a major increase in BTV-8 transmission.We also found that the applied disease control (spatial zones based on 20 km radius restricting animal transport to outside regions) led to a spatial transmission pattern of BTV-8, with 85% of transmission restricted to a 20 km range. This 20 km equals the scale of the protection zones. We concluded that free animal movement led to substantial faster spread of the BTV-8 epidemic over space as compared to a situation with animal movement restrictions.

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“…This has resulted in increased research activities in virus transmission, on detailed reporting of these outbreaks [24], [25] and in initiation of modelling studies, for example [26]–[28].…”

Section: Introductionmentioning

confidence: 99%

A Spatial Simulation Model for the Dispersal of the Bluetongue Vector Culicoides brevitarsis in Australia

Kelso

Milne

2014

PLoS ONE

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BackgroundThe spread of Bluetongue virus (BTV) among ruminants is caused by movement of infected host animals or by movement of infected Culicoides midges, the vector of BTV. Biologically plausible models of Culicoides dispersal are necessary for predicting the spread of BTV and are important for planning control and eradication strategies.MethodsA spatially-explicit simulation model which captures the two underlying population mechanisms, population dynamics and movement, was developed using extensive data from a trapping program for C. brevitarsis on the east coast of Australia. A realistic midge flight sub-model was developed and the annual incursion and population establishment of C. brevitarsis was simulated. Data from the literature was used to parameterise the model.ResultsThe model was shown to reproduce the spread of C. brevitarsis southwards along the east Australian coastline in spring, from an endemic population to the north. Such incursions were shown to be reliant on wind-dispersal; Culicoides midge active flight on its own was not capable of achieving known rates of southern spread, nor was re-emergence of southern populations due to overwintering larvae. Data from midge trapping programmes were used to qualitatively validate the resulting simulation model.ConclusionsThe model described in this paper is intended to form the vector component of an extended model that will also include BTV transmission. A model of midge movement and population dynamics has been developed in sufficient detail such that the extended model may be used to evaluate the timing and extent of BTV outbreaks. This extended model could then be used as a platform for addressing the effectiveness of spatially targeted vaccination strategies or animal movement bans as BTV spread mitigation measures, or the impact of climate change on the risk and extent of outbreaks. These questions involving incursive Culicoides spread cannot be simply addressed with non-spatial models.

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Bluetongue in Belgium: Episode II

Cited by 29 publications

References 12 publications

Virus and Host Factors Affecting the Clinical Outcome of Bluetongue Virus Infection

Virus and Host Factors Affecting the Clinical Outcome of Bluetongue Virus Infection

Quantitative analysis of transmission parameters for bluetongue virus serotype 8 in Western Europe in 2006

A Spatial Simulation Model for the Dispersal of the Bluetongue Vector Culicoides brevitarsis in Australia

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