Spatial distribution of Culicoides imicola, the main vector of bluetongue virus, in Spain

The distribution of Bluetongue virus (BTV) in Europe can be represented by two distinct and interconnected epidemiological systems (episystems), each characterized by different ecological characteristics and vector species. This study investigated the vector competence of Italian populations of Culicoides imicola and Culicoides obsoletus/scoticus to some representative BTV strains after artificial oral infection. The BTV strains were selected according to their ability to spread to one or both episystems and included BTV-4 ITA, responsible of the recent Italian and French BTV-4 outbreaks; the BTV-2 strain which caused the first BTV incursion in Italy, Corsica, and Balearic Islands; BTV-4 MOR, responsible for the epidemic in Morocco; and BTV-8, the strain which spread through Europe between 2006 and 2008. Blood-soaked cotton pledgets and Hemotek membrane feeder using Parafilm® membrane were used to artificially feed midges. For each population/strain, recovery rates (positive/tested heads) were evaluated using serogroup- and serotype-specific RT-PCR. The trial demonstrated that, except for the Abruzzo population of C. obsoletus/C. scoticus, which was refractory to BTV-4 MOR infection, all the investigated Culicoides populations are susceptible to the selected BTV strains and that, if prompt vaccination programs and restriction measures had not been implemented, BTV-2 and BTV-4 MOR could have spread all over Europe.

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Further studies on bluetongue and bluetongue-related Orbiviruses in the Sudan

Epidemiology and Infection ◽

10.1017/s0950268800048263 ◽

1990 ◽

Vol 105 (3) ◽

pp. 619-632 ◽

Cited By ~ 25

Author(s):

M. E. H. Mohammed ◽

P. S. Mellor

Keyword(s):

Rainy Season ◽

Bluetongue Virus ◽

Population Densities ◽

Seasonal Incidence ◽

Central Sudan ◽

Culicoides Imicola ◽

The Status ◽

Haemorrhagic Disease ◽

First Time ◽

Virus Isolates

SUMMARYThe seasonal incidence of bluetongue virus (BTV) in Central Sudan is related primarily to fluctuations in the prevalence of the vector, Culicoides imicola. Population densities of this midge begin to rise with the onset of precipitation and peak during October, before falling sharply at the end of the rainy season in November. These are also the months of BTV transmission. Populations of C. schultzei, the commonest midge in Central Sudan, are also related to the rainy season but this species does not seem to be involved with BTV transmission.BTV serotype 2 was isolated from C. imicola confirming the status of this midge as a known vector but a second isolate of the same serotype was made from a mixed pool of Culicoides not including C. imicola. This suggests that BTV transmission in the Sudan may involve more than one species of Culicoides. Epizootic haemorrhagic disease virus (EHDV) serotype 4 and a palyam virus were isolated from C. schultzei which indicates that this species may be involved in the transmission of BT-related viruses. Seven further virus isolates from sentinel calves at Shambat (Khartoum) confirmed the presence of BTV serotypes 1, 4 and 16, and an untyped EHDV (designated 318) in the Sudan. All of the viruses isolated and identified during the course of this work are recorded from the Sudan for the first time.

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Epidemiology and spatial distribution of bluetongue virus in Xinjiang, China

PeerJ ◽

10.7717/peerj.6514 ◽

2019 ◽

Vol 7 ◽

pp. e6514 ◽

Cited By ~ 4

Author(s):

Jun Ma ◽

Xiang Gao ◽

Boyang Liu ◽

Hao Chen ◽

Jianhua Xiao ◽

...

Keyword(s):

Spatial Distribution ◽

Spatial Autocorrelation ◽

Bluetongue Virus ◽

Large Scale ◽

Economic Losses ◽

Random Pattern ◽

Diurnal Range ◽

Precipitation Seasonality ◽

Risk Areas ◽

Global Spatial Autocorrelation

Bluetongue (BT) is a non-contagious disease affecting domestic and wild ruminants. Outbreaks of BT can cause serious economic losses. To investigate the distribution characteristics of bluetongue virus (BTV), two large-scale censuses of BTV prevalence in Xinjiang, China were collected. Spatial autocorrelation analysis, including global spatial autocorrelation and local spatial autocorrelation, was performed. Risk areas for BTV occurrence in Xinjiang were detected using the presence-only maximum entropy model. The global spatial autocorrelation of BTV distribution in Xinjiang in 2012 showed a random pattern. In contrast, the spatial distribution of BTV from 2014 to 2015 was significantly clustered. The hotspot areas for BTV infection included Balikun County (p< 0.05), Yiwu County (p< 0.05) and Hami City (p< 0.05) in 2012. These three regions were also hotspot areas during 2014 and 2015. Sheep distribution (25.6% contribution), precipitation seasonality (22.1% contribution) and mean diurnal range (16.2% contribution) were identified as the most important predictors for BTV occurrence in Xinjiang. This study demonstrated the presence of high-risk areas for BTV infection in Xinjiang, which can serve as a tool to aid in the development of preventative countermeasures of BT outbreaks.

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Moucherons piqueurs (Ceratopogonidae: Culicoides Latreille) rencontrés dans les fermes en Suède

Revue d’élevage et de médecine vétérinaire des pays tropicaux ◽

10.19182/remvt.10050 ◽

2009 ◽

Vol 62 (2-4) ◽

pp. 140

Author(s):

S. A. Nielsen ◽

B. O. Nielsen ◽

J. Chirico

Keyword(s):

Spatial Distribution ◽

Relative Abundance ◽

Bluetongue Virus ◽

Northern Europe ◽

Culicoides Species ◽

Livestock Farms

In light of the emergence of bluetongue in Northern Europe, populations of Culicoides species were monitored in and around several Swedish livestock farms (surveillance in 2007 and 2008). The position of the sampling sites ranged from about latitude 55° N to about 68° N. Thirty-three Culicoides species were recorded, of which 30 were new to Sweden. The species recorded, and their relative abundance and spatial distribution on sites are detailed. Species incriminated as vectors of bluetongue virus were predominant.

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