Modelo epidemiológico de difusión de la influenza aviar altamente patógena (IAAP)
PhD Thesis defense by Irene Iglesias Martín at the Faculty of Veterinary Medicine of the Complutense University of Madrid
April 27th, 2011
The aim of this thesis is to identify which areas present a higher risk of spread of Highly Pathogenic Avian Influenza (HPAI) in Spain and to evaluate the consequences that this diffusion would involve, to contribute to the improvement surveillance and control plans against the disease, both wild and domesticated birds. To this aim, it has been developed a diffusion model of HPAI highly adapted to the structural characteristics of our poultry sector, which includes two different stages, the industrial poultry farming of chickens, and backyard poultry combined with no-chicken poultry farm wich including several avian species. The model comprises a first part in each scene in which different zones have been identified according to the risk of diffusion, based on information available from poultry farms, their location and their risk factors. Within the industrial poultry farming of chickens, it has been made a second part consisting of a dynamic stochastic model to simulate an epidemic of HPAI. It has been used as a territorial model the region of Castilla-Leon (CyL), which has been selected not only for being the reflect of the Spanish poultry’s situation, but because in some of its provinces it has been identified high risk introduction areas of HPAI in wild birds and live poultry trade. (Martínez et al., 2008; Martínez et al., 2009, Sánchez-Vizcaíno et al., 2010; Iglesias et al., 2010a).
HPAI is one of the most important infectious viral diseases of poultry due to its high contagious power, its high mortality rate and the huge economic losses, both direct and indirect, that causes in the affected countries. It is a notifiable disease under the OIE so its presence in any country has serious implications for animal’s international trade and avian origin products. HP H5N1 subtype has had a rapid spread in recent years affecting between 2004 and 2009 more than 60 countries, causing significant economic losses and also a large social alarm due to fatal cases in people. Outbreaks have notified in Central Asia Middle East, Europe and Africa in both domestic and wild poultry. Although Spain has just been two occasional outbreaks (in 2006 and 2009) who have not spread, the disease’s risk of introduction is a reality, partly due to the importance that this sector represents (ranked third in poultry production European level) and the live birds large amount of import of which depends our production, and, moreover, the wild birds movement, because Spain hosts many susceptible migratory wild birds to HPAI from countries with high infection’s probability (Martinez et al., 2009). Therefore, the high impact that the spread of HPAI can have on health and economy in Spain, has been one of the main reasons which has motivated the development of this work. Another reason was the lack of previous work in this subject in our country, and so far it has not been developed any HPAI spreading model of risk adapted to the environmental, geographic and structural characteristics of Spain, in order to analyze an HPAI introduction’s consequences. Therefore, the study presented here is innovative and let’s generate information so far not available which is designed to improve human and economic efforts in the fight against this disease. The developed model can be updated continuously according with the policy and structural changes in the sector, to provide current information for answers according with the reality of our country at all times
