Anthropogenic factors and the risk of highly pathogenic avian influenza H5N1: prospects from a spatial-based model |
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| Authors: | Mathilde Paul Saraya Tavornpanich David Abrial Patrick Gasqui Myriam Charras-Garrido Weerapong Thanapongtharm Xiangming Xiao Marius Gilbert Francois Roger and Christian Ducrot |
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| Institution: | 1
INRA, UR 346 F-63122
Saint-Genès-Champanelle France;2
Unité AGIRs, CIRAD France;3
Department of Livestock Development Bangkok Thailand;4
Department of Botany and Microbiology, Center for Spatial Analysis, University of Oklahoma Norman OK 73019 USA;5
Biological Control and spatial Ecology, Université Libre de Bruxelles Belgium;6
Fonds National de la Recherche Scientifique Brussels Belgium |
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| Abstract: | Beginning in 2003, highly pathogenic avian influenza (HPAI) H5N1 virus spread across Southeast Asia, causing unprecedented epidemics. Thailand was massively infected in 2004 and 2005 and continues today to experience sporadic outbreaks. While research findings suggest that the spread of HPAI H5N1 is influenced primarily by trade patterns, identifying the anthropogenic risk factors involved remains a challenge. In this study, we investigated which anthropogenic factors played a role in the risk of HPAI in Thailand using outbreak data from the “second wave” of the epidemic (3 July 2004 to 5 May 2005) in the country. We first performed a spatial analysis of the relative risk of HPAI H5N1 at the subdistrict level based on a hierarchical Bayesian model. We observed a strong spatial heterogeneity of the relative risk. We then tested a set of potential risk factors in a multivariable linear model. The results confirmed the role of free-grazing ducks and rice-cropping intensity but showed a weak association with fighting cock density. The results also revealed a set of anthropogenic factors significantly linked with the risk of HPAI. High risk was associated strongly with densely populated areas, short distances to a highway junction, and short distances to large cities. These findings highlight a new explanatory pattern for the risk of HPAI and indicate that, in addition to agro-environmental factors, anthropogenic factors play an important role in the spread of H5N1. To limit the spread of future outbreaks, efforts to control the movement of poultry products must be sustained. |
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| Keywords: | avian influenza epidemiology poultry farming spatial analysis Thailand |
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