Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015
Abstract Background From 2006 to 2010, France experienced two bluetongue epidemics caused by serotype 1 (BTV-1) and 8 (BTV-8) which were controlled by mass vaccination campaigns. After five years without any detected cases, a sick ram was confirmed in August 2015 to be infected by a BTV-8 strain alm...
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| Format: | Article |
| Language: | English |
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BMC
2018-03-01
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| Series: | BMC Veterinary Research |
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| Online Access: | http://link.springer.com/article/10.1186/s12917-018-1388-1 |
| _version_ | 1819123479654432768 |
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| author | L. Bournez L. Cavalerie C. Sailleau E. Bréard G. Zanella R. Servan de Almeida A. Pedarrieu E. Garin I. Tourette F. Dion P. Hendrikx D. Calavas |
| author_facet | L. Bournez L. Cavalerie C. Sailleau E. Bréard G. Zanella R. Servan de Almeida A. Pedarrieu E. Garin I. Tourette F. Dion P. Hendrikx D. Calavas |
| author_sort | L. Bournez |
| collection | DOAJ |
| description | Abstract Background From 2006 to 2010, France experienced two bluetongue epidemics caused by serotype 1 (BTV-1) and 8 (BTV-8) which were controlled by mass vaccination campaigns. After five years without any detected cases, a sick ram was confirmed in August 2015 to be infected by a BTV-8 strain almost identical to that circulating during the previous outbreak. By then, part of the French cattle population was expected to be still protected, since bluetongue antibodies are known to last for many years after natural infection or vaccination. The objective of this study was to estimate the proportion of cattle in France still immune to BTV-8 at the time of its re-emergence in 2015. Results We used BTV group-specific cELISA results from 8525 cattle born before the vaccination ban in 2013 and 15,799 cattle born after the ban. Samples were collected from January to April 2016 to estimate seroprevalence per birth cohort. The overall seroprevalence in cattle at national and local levels was extrapolated from seroprevalence results per birth cohort and their respective proportion at each level. To indirectly assess pre-immune status of birth cohorts, we computed prevalence per birth cohort on infected farms in autumn 2015 using 1377 RT-PCR results. These revealed limited BTV circulation in 2015. Seroprevalence per birth cohort was likely to be connected to past exposure to natural infection and/or vaccination with higher seroprevalence levels in older animals. A seroprevalence of 95% was observed for animals born before 2008, of which > 90% were exposed to two compulsory vaccination campaigns in 2008-2010. None of the animals born before 2008 were found to be infected, unlike 19% of the young cattle which had never been vaccinated. This suggests that most ELISA-positive animals were pre-immune to BTV-8. We estimated that 18% (from 12% to 32% per département) of the French cattle population was probably pre-immune in 2015. Conclusions These results strongly suggest a persistence of antibodies for at least 5-6 years after natural infection or vaccination. The herd immunity of the French cattle population probably limited BTV circulation up to 2015, by which time more than 80% of cattle were naive. |
| first_indexed | 2024-12-22T07:09:00Z |
| format | Article |
| id | doaj.art-7c65a37934284f3d82d75ba2399c9692 |
| institution | Directory Open Access Journal |
| issn | 1746-6148 |
| language | English |
| last_indexed | 2024-12-22T07:09:00Z |
| publishDate | 2018-03-01 |
| publisher | BMC |
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| series | BMC Veterinary Research |
| spelling | doaj.art-7c65a37934284f3d82d75ba2399c96922022-12-21T18:34:35ZengBMCBMC Veterinary Research1746-61482018-03-0114111110.1186/s12917-018-1388-1Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015L. Bournez0L. Cavalerie1C. Sailleau2E. Bréard3G. Zanella4R. Servan de Almeida5A. Pedarrieu6E. Garin7I. Tourette8F. Dion9P. Hendrikx10D. Calavas11ANSES (French Agency for Food, Environmental and Occupational Health & Safety), Unité de coordination et d’appui à la surveillance, Direction des laboratoiresMinistère en charge de l’Agriculture, Direction générale de l’Alimentation, Bureau de la santé animaleANSES, Laboratoire de santé animale, Université Paris-EstANSES, Laboratoire de santé animale, Université Paris-EstANSES, Laboratoire de santé animale, Université Paris-EstCIRAD, UMR ASTRE, Montpellier ; Inra, UMR ASTRECIRAD, UMR ASTRE, Montpellier ; Inra, UMR ASTRECoop de FranceGDS FranceRaces de FranceANSES (French Agency for Food, Environmental and Occupational Health & Safety), Unité de coordination et d’appui à la surveillance, Direction des laboratoiresANSES, Laboratoire de Lyon, Unité Epidémiologie, Laboratoire de LyonAbstract Background From 2006 to 2010, France experienced two bluetongue epidemics caused by serotype 1 (BTV-1) and 8 (BTV-8) which were controlled by mass vaccination campaigns. After five years without any detected cases, a sick ram was confirmed in August 2015 to be infected by a BTV-8 strain almost identical to that circulating during the previous outbreak. By then, part of the French cattle population was expected to be still protected, since bluetongue antibodies are known to last for many years after natural infection or vaccination. The objective of this study was to estimate the proportion of cattle in France still immune to BTV-8 at the time of its re-emergence in 2015. Results We used BTV group-specific cELISA results from 8525 cattle born before the vaccination ban in 2013 and 15,799 cattle born after the ban. Samples were collected from January to April 2016 to estimate seroprevalence per birth cohort. The overall seroprevalence in cattle at national and local levels was extrapolated from seroprevalence results per birth cohort and their respective proportion at each level. To indirectly assess pre-immune status of birth cohorts, we computed prevalence per birth cohort on infected farms in autumn 2015 using 1377 RT-PCR results. These revealed limited BTV circulation in 2015. Seroprevalence per birth cohort was likely to be connected to past exposure to natural infection and/or vaccination with higher seroprevalence levels in older animals. A seroprevalence of 95% was observed for animals born before 2008, of which > 90% were exposed to two compulsory vaccination campaigns in 2008-2010. None of the animals born before 2008 were found to be infected, unlike 19% of the young cattle which had never been vaccinated. This suggests that most ELISA-positive animals were pre-immune to BTV-8. We estimated that 18% (from 12% to 32% per département) of the French cattle population was probably pre-immune in 2015. Conclusions These results strongly suggest a persistence of antibodies for at least 5-6 years after natural infection or vaccination. The herd immunity of the French cattle population probably limited BTV circulation up to 2015, by which time more than 80% of cattle were naive.http://link.springer.com/article/10.1186/s12917-018-1388-1BluetongueSerotype 8SeroprevalenceHerd immunityRe-emergenceFrance |
| spellingShingle | L. Bournez L. Cavalerie C. Sailleau E. Bréard G. Zanella R. Servan de Almeida A. Pedarrieu E. Garin I. Tourette F. Dion P. Hendrikx D. Calavas Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 BMC Veterinary Research Bluetongue Serotype 8 Seroprevalence Herd immunity Re-emergence France |
| title | Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 |
| title_full | Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 |
| title_fullStr | Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 |
| title_full_unstemmed | Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 |
| title_short | Estimation of French cattle herd immunity against bluetongue serotype 8 at the time of its re-emergence in 2015 |
| title_sort | estimation of french cattle herd immunity against bluetongue serotype 8 at the time of its re emergence in 2015 |
| topic | Bluetongue Serotype 8 Seroprevalence Herd immunity Re-emergence France |
| url | http://link.springer.com/article/10.1186/s12917-018-1388-1 |
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