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Bluetongue epidemiology in the European Union.

Saegerman C, Berkvens D, Mellor PS - Emerging Infect. Dis. (2008)

Bottom Line: Since August 2006, BTV-8 has caused a severe epizootic of BT in northern Europe.In addition, the radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin, where vector activity continues for more of the year.This condition increases the risk for reassortment of individual BTV gene segments.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious and Parasitic Diseases, Epidemiology and Risk Analysis Applied to Veterinary, University of Liège, Liège, Belgium. claude.saegerman@ulg.ac.be

ABSTRACT
Bluetongue (BT) is a reportable disease of considerable socioeconomic concern and of major importance in the international trade of animals and animal products. Before 1998, BT was considered an exotic disease in Europe. From 1998 through 2005, at least 6 BT virus strains belonging to 5 serotypes (BTV-1, BTV-2, BTV-4, BTV-9, and BTV-16) were continuously present in the Mediterranean Basin. Since August 2006, BTV-8 has caused a severe epizootic of BT in northern Europe. The widespread recrudescence and extension of BTV-8 infections in northern Europe during 2007 suggest that requirements for BTV establishment may now be fulfilled in this area. In addition, the radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin, where vector activity continues for more of the year. This condition increases the risk for reassortment of individual BTV gene segments.

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Bluetongue virus (BTV) restriction zones in Europe, by serotype. The radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and other serotypes that occur in the Mediterranean Basin (second epidemiologic system, where serotypes BTV-1, BTV-2, BTV-4, and BTV-16 were identified and the main vector is Culicoides imicola). This situation increases the risk for reassortment of individual BTV gene segments, and, in the more southerly areas, the period of vector activity is also likely to extend, leading to a longer BTV-8 season. In addition, BTV-1, which was first identified in sheep with clinical signs of BT in the south of the Iberian Peninsula in July 2007, has extended its range into northern Spain and southwestern France (Pyrénées-Atlantiques), since November 2007; this ongoing expansion is matter of major concern.
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Figure 6: Bluetongue virus (BTV) restriction zones in Europe, by serotype. The radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and other serotypes that occur in the Mediterranean Basin (second epidemiologic system, where serotypes BTV-1, BTV-2, BTV-4, and BTV-16 were identified and the main vector is Culicoides imicola). This situation increases the risk for reassortment of individual BTV gene segments, and, in the more southerly areas, the period of vector activity is also likely to extend, leading to a longer BTV-8 season. In addition, BTV-1, which was first identified in sheep with clinical signs of BT in the south of the Iberian Peninsula in July 2007, has extended its range into northern Spain and southwestern France (Pyrénées-Atlantiques), since November 2007; this ongoing expansion is matter of major concern.

Mentions: The widespread recrudescence of BTV-8 infections in northern France, Belgium, the Netherlands, Luxembourg, and Germany in 2007 and the emergence of BTV-8 in the United Kingdom, Denmark, Switzerland, and the Czech Republic in the same year suggest that the requirements for BTV establishment may now also be fulfilled in many more northerly and central parts of Europe (in the absence of C. imicola). In addition, the radial extension of BTV-8 across Europe (including the jump across the English Channel) (Figure 5) (39) increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin (second epidemiologic system). BTV serotypes 1, 2, 4, and 16 have been identified in this area, and the addition of a further serotype will considerably increase the potential for reassortment between these viruses (Figure 6) (27,40). Indeed, the number of possible reassortments in the case of BTV, which has 10 segments, increases with the number of cocirculating serotypes (e.g., 1,024 for 2 serotypes [210] and 59,049 for 3 serotypes [310]) (4). Moreover, the phenomenon of reassortment has already been demonstrated during the 1998–2005 BTV outbreaks in Europe (5).


Bluetongue epidemiology in the European Union.

Saegerman C, Berkvens D, Mellor PS - Emerging Infect. Dis. (2008)

Bluetongue virus (BTV) restriction zones in Europe, by serotype. The radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and other serotypes that occur in the Mediterranean Basin (second epidemiologic system, where serotypes BTV-1, BTV-2, BTV-4, and BTV-16 were identified and the main vector is Culicoides imicola). This situation increases the risk for reassortment of individual BTV gene segments, and, in the more southerly areas, the period of vector activity is also likely to extend, leading to a longer BTV-8 season. In addition, BTV-1, which was first identified in sheep with clinical signs of BT in the south of the Iberian Peninsula in July 2007, has extended its range into northern Spain and southwestern France (Pyrénées-Atlantiques), since November 2007; this ongoing expansion is matter of major concern.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2570923&req=5

Figure 6: Bluetongue virus (BTV) restriction zones in Europe, by serotype. The radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and other serotypes that occur in the Mediterranean Basin (second epidemiologic system, where serotypes BTV-1, BTV-2, BTV-4, and BTV-16 were identified and the main vector is Culicoides imicola). This situation increases the risk for reassortment of individual BTV gene segments, and, in the more southerly areas, the period of vector activity is also likely to extend, leading to a longer BTV-8 season. In addition, BTV-1, which was first identified in sheep with clinical signs of BT in the south of the Iberian Peninsula in July 2007, has extended its range into northern Spain and southwestern France (Pyrénées-Atlantiques), since November 2007; this ongoing expansion is matter of major concern.
Mentions: The widespread recrudescence of BTV-8 infections in northern France, Belgium, the Netherlands, Luxembourg, and Germany in 2007 and the emergence of BTV-8 in the United Kingdom, Denmark, Switzerland, and the Czech Republic in the same year suggest that the requirements for BTV establishment may now also be fulfilled in many more northerly and central parts of Europe (in the absence of C. imicola). In addition, the radial extension of BTV-8 across Europe (including the jump across the English Channel) (Figure 5) (39) increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin (second epidemiologic system). BTV serotypes 1, 2, 4, and 16 have been identified in this area, and the addition of a further serotype will considerably increase the potential for reassortment between these viruses (Figure 6) (27,40). Indeed, the number of possible reassortments in the case of BTV, which has 10 segments, increases with the number of cocirculating serotypes (e.g., 1,024 for 2 serotypes [210] and 59,049 for 3 serotypes [310]) (4). Moreover, the phenomenon of reassortment has already been demonstrated during the 1998–2005 BTV outbreaks in Europe (5).

Bottom Line: Since August 2006, BTV-8 has caused a severe epizootic of BT in northern Europe.In addition, the radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin, where vector activity continues for more of the year.This condition increases the risk for reassortment of individual BTV gene segments.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious and Parasitic Diseases, Epidemiology and Risk Analysis Applied to Veterinary, University of Liège, Liège, Belgium. claude.saegerman@ulg.ac.be

ABSTRACT
Bluetongue (BT) is a reportable disease of considerable socioeconomic concern and of major importance in the international trade of animals and animal products. Before 1998, BT was considered an exotic disease in Europe. From 1998 through 2005, at least 6 BT virus strains belonging to 5 serotypes (BTV-1, BTV-2, BTV-4, BTV-9, and BTV-16) were continuously present in the Mediterranean Basin. Since August 2006, BTV-8 has caused a severe epizootic of BT in northern Europe. The widespread recrudescence and extension of BTV-8 infections in northern Europe during 2007 suggest that requirements for BTV establishment may now be fulfilled in this area. In addition, the radial extension of BTV-8 across Europe increases the risk for an encounter between this serotype and others, particularly those that occur in the Mediterranean Basin, where vector activity continues for more of the year. This condition increases the risk for reassortment of individual BTV gene segments.

Show MeSH
Related in: MedlinePlus