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22 October 2012 Historical, Spatial, Temporal, and Time-Space Epidemiology of Very Virulent Infectious Bursal Disease in California: A Retrospective Study 2008–2011
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In December of 2008 very virulent infectious bursal disease virus (vvIBDV) was identified in a commercial flock in northern California. Since then several other backyard and commercial facilities in California have had flocks affected by the same strain and other unique (previously unseen) strains of IBDV. Previous to this incident, very virulent infectious bursal disease (vvIBD) had never been identified in North America. Following the initial outbreak in 2008, California became the first state to undertake a voluntary surveillance effort to try to determine the geographical prevalence of vvIBD based on sequencing of a portion of the segment A region of the vvIBDV genome. To date we have complete geographical information on approximately 500 separate accessions representing approximately 1500 birds from over 200 commercial (∼85% of the facilities) and backyard facilities (∼15% of the facilities) throughout the state. Sequencing of targeted regions of both the segment A and segment B regions of the genome has revealed three distinct types of IBDV in California chickens. One type is genetically and in pathogenically consistent with vvIBDV. The second and third types only have a segment A region consistent with vvIBDV. Geographic information system mapping coupled with spatial-temporal cluster analysis identified significant spatial and time-space clustering; however, no temporal clustering was noted. The lack of temporal clustering coupled with negative vvIBDV results in tested avian wildlife implies that avian wildlife in California do not currently appear to play a significant role in vvIBDV transmission. In the voluntary surveillance that was done in the Central Valley of California, which has a high density of commercial poultry, no positive farms were found when 142 of 504 farms were sampled. Given this level of sampling, the confidence (probability) of detecting an affected commercial flock was calculated to be between 28% and 81% depending on whether one or five hypothetically affected farms were affected.

Epidemiología histórica, espacial y espacio-temporal del virus muy virulento de la enfermedad infecciosa de la bolsa en California: Un estudio retrospectivo 2008–2011.

En diciembre del 2008, se identificó un virus muy virulento de la enfermedad infecciosa de la bolsa (con las siglas en inglés vvIBDV) en un lote comercial en el norte de California. Desde entonces, varias instalaciones avícolas comerciales y de traspatio en California han tenido parvadas afectadas por la misma cepa y otra cepa única (no detectada anteriormente) del virus de Gumboro. Antes de este incidente, el virus muy virulento de la enfermedad infecciosa de la bolsa nunca había sido identificado en América del Norte. Después del brote inicial en el año 2008, California se convirtió en el primer estado en realizar un esfuerzo voluntario de vigilancia para determinar la prevalencia geográfica del virus muy virulento de Gumboro basado en el análisis de secuencias de una porción del segmento A del genoma de este virus muy virulento. Hasta la fecha se cuenta con información geográfica completa de aproximadamente 500 registros de diagnóstico diferentes que representan aproximadamente 1,500 aves de más de 200 instalaciones comerciales (aproximadamente el 85% de las instalaciones) y de las instalaciones de traspatio (aproximadamente el 15% de las instalaciones) en todo el estado. El análisis de las secuencias de las regiones blanco de los segmentos A y B del genoma ha revelado tres tipos distintos de cepas del virus de Gumboro en pollos de California. Un tipo es genética y patogénicamente similar con el virus muy virulento de Gumboro. El segundo y tercer tipos solo tienen un segmento A similar a las cepas virulentas. El mapeo por sistemas de información geográfica (con las siglas en inglés GIS), junto con el análisis de conglomerados espacio-temporales identificaron agrupamientos espaciales y espac

American Association of Avian Pathologists
Maurice Pitesky, Kristina Cataline, Beate Crossley, Michael Poulos, Greg Ramos, Dave Willoughby, Peter Woolcock, Gregg Cutler, Mark Bland, Johnny Tran, Daral Jackwood, Larry Allen, Rich Breitmeyer, Annette Jones, Kenneth Forsythe, C. Gabriel Sentíes-Cué, and Bruce Charlton "Historical, Spatial, Temporal, and Time-Space Epidemiology of Very Virulent Infectious Bursal Disease in California: A Retrospective Study 2008–2011," Avian Diseases 57(1), 76-82, (22 October 2012).
Received: 16 July 2012; Accepted: 1 October 2012; Published: 22 October 2012

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