Contact structures in the poultry industry in Great Britain: Exploring transmission routes for a potential avian influenza virus epidemic

Poultry premises using multiple slaughterhouses lead to a large number of premises being potentially connected, with the resultant potential for large and sometimes widespread epidemics. Catching companies can also potentially link a large proportion of the poultry population. Critical to this is the maximum distance traveled by catching companies between premises and whether or not between-species transmission could occur within individual premises. Premises closely linked by proximity may result in connections being formed between different species and or sectors within the industry.Even quite well-contained epidemics have the potential for geographically widespread dissemination, potentially resulting in severe logistical problems for epidemic control, and with economic impact on a large part of the country. Premises sending birds to multiple slaughterhouses or housing multiple species may act as a bridge between otherwise separate sectors of the industry, resulting in the potential for large epidemics. Investment into further data collection and analyses on the importance of industry structure as a determinant for spread of AIV would enable us to use the results from this study to contribute to policy on disease control.The GB commercial poultry industry is an important industry to the British government, the consumer and farmers alike. Worth an estimated ￡3.4 billion at retail value, producing over 174 million birds for consumption per year [1], poultry diseases are of widespread interest, both from the point-of-view of understanding different poultry farming methods [2-4], and in terms of studying the potential impact of different diseases on poultry [5-7]. However, our knowledge of how poultry farms in GB are connected to each other by the movement of people and equipment is more limited. This is essential for effective prevention and control for potential outbreaks of diseases transmitted by the movement of people and equipment between farms within the comme