Epidemiological consequences of an incursion of highly pathogenic H5N1 avian influenza into the British poultry flock

Abstract

Highly pathogenic avian influenza and in particular the H5N1 strain has resulted in the culling of millions of birds and continues to pose a threat to poultry industries worldwide. The recent outbreak of H5N1 in the UK highlights the need for detailed assessment of the consequences of an incursion and of the efficacy of control strategies. Here, we present results from a model of H5N1 propagation within the British poultry industry. We find that although the majority of randomly seeded incursions do not spread beyond the initial infected premises, there is significant potential for widespread infection. The efficacy of the European Union strategy for disease control is evaluated and our simulations emphasize the pivotal role of duck farms in spreading H5N1.

Transmissibility of the highly pathogenic avian influenza virus, subtype H5N1 in domestic poultry: a spatio-temporal estimation at the global scale

“…Previous studies only focused on one dimension of disease transmissibility, which could result in the loss of useful information. It is well known that R 0 is affected by many factors, including epidemiological, demographic and geographical features; density being perhaps the most important influence of HPAIV H5N1 transmission, at least in domestic poultry (Keeling and Eames, 2005;Sharkey et al, 2008;Soares Magalhães et al, 2010). We found that the magnitudes of correlation coefficients between R 0 and poultry density were all very small.…”

Modelling control of avian influenza in poultry: the link with data

“…Le Menach et al (6) have used three different probabilities for three different distance bands and estimated these from the data. In contrast, Sharkey et al (8) have only used one probability for the nearest neighbours of an IP, which they estimated from the literature.…”

“…Conclusions based on statistical inference are typically robust, although they only apply to the specific situation studied. For example, it is obvious that major HPAI outbreaks can occur in areas with high densities of poultry farms even with control measures in place (1,5,8).…”

Preventable H5N1 avian influenza epidemics in the British poultry industry network exhibit characteristic scales

“…Although the true likelihoods are still mooted, they likely do not exceed the parameter ranges explored. We furthermore compared a basic control (BC) policy of increased biosecurity, bans on livestock movements and culling upon detection (the latter with species-dependent delays) to the more stringent European Union (EU) controls, which add 3 km protection and 10 km surveillance zones plus dangerous contact-tracing (all sites directly connected to an infected one are treated as if within a protection zone); see electronic supplementary material (Eames & Keeling 2003;Dybiec et al 2004;Kiss et al 2005Kiss et al , 2006Capua & Alexander 2006;Truscott et al 2007;Sharkey et al 2008).…”

“…All models incorporate four different types of transmission: local spread, feed deliveries, abattoir transports and within-company movements (Sharkey et al 2008). The poultry farms constitute the network nodes; the simulated local spreading plus transport movements of feed, slaughter and company lorries that serve multiple farms comprise about one quarter million (undirected) links between nodes, with specific transmission strengths (table 1).…”