sharon sanders
Editor-in-Chief & President
The Transmissibility of Highly Pathogenic Avian Influenza in Commercial Poultry in Industrialised Countries
Tini Garske1,2*, Paul Clarke1, Azra C. Ghani1
1 Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom, 2 Institute for Mathematical Sciences, Imperial College London, London, United Kingdom
Background
With the increased occurrence of outbreaks of H5N1 worldwide there is concern that the virus could enter commercial poultry farms with severe economic consequences.
Methodology/Principal Findings
We analyse data from four recent outbreaks of highly pathogenic avian influenza (HPAI) in commercial poultry to estimate the farm-to-farm reproductive number for HPAI. The reproductive number is a key measure of the transmissibility of HPAI at the farm level because it can be used to evaluate the effectiveness of the control measures. In these outbreaks the mean farm-to-farm reproductive number prior to controls ranged from 1.1 to 2.4, with the maximum farm-based reproductive number in the range 2.2 to 3.2. Enhanced bio-security, movement restrictions and prompt isolation of the infected farms in all four outbreaks substantially reduced the reproductive number, but it remained close to the threshold value 1 necessary to ensure the disease will be eradicated.
Conclusions/Significance
Our results show that depending on the particular situation in which an outbreak of avian influenza occurs, current controls might not be enough to eradicate the disease, and therefore a close monitoring of the outbreak is required. The method we used for estimating the reproductive number is straightforward to implement and can be used in real-time. It therefore can be a useful tool to inform policy decisions.
Funding: This work was supported by research funding from the UK Department for Environment, Food and Rural Affairs. The views expressed in the paper are those of the authors.
Competing interests: The authors have declared that no competing interests exist.
Academic Editor: Enrico Scalas, University of East Piedmont, Italy
Citation: Garske T, Clarke P, Ghani AC (2007) The Transmissibility of Highly Pathogenic Avian Influenza in Commercial Poultry in Industrialised Countries. PLoS ONE 2(4): e349. doi:10.1371/journal.pone.0000349
Received: February 6, 2007; Accepted: March 14, 2007; Published: April 4, 2007
Copyright: ? 2007 Garske et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
* To whom correspondence should be addressed. E-mail: t.garske@imperial.ac.uk
http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0000349
Tini Garske1,2*, Paul Clarke1, Azra C. Ghani1
1 Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom, 2 Institute for Mathematical Sciences, Imperial College London, London, United Kingdom
Background
With the increased occurrence of outbreaks of H5N1 worldwide there is concern that the virus could enter commercial poultry farms with severe economic consequences.
Methodology/Principal Findings
We analyse data from four recent outbreaks of highly pathogenic avian influenza (HPAI) in commercial poultry to estimate the farm-to-farm reproductive number for HPAI. The reproductive number is a key measure of the transmissibility of HPAI at the farm level because it can be used to evaluate the effectiveness of the control measures. In these outbreaks the mean farm-to-farm reproductive number prior to controls ranged from 1.1 to 2.4, with the maximum farm-based reproductive number in the range 2.2 to 3.2. Enhanced bio-security, movement restrictions and prompt isolation of the infected farms in all four outbreaks substantially reduced the reproductive number, but it remained close to the threshold value 1 necessary to ensure the disease will be eradicated.
Conclusions/Significance
Our results show that depending on the particular situation in which an outbreak of avian influenza occurs, current controls might not be enough to eradicate the disease, and therefore a close monitoring of the outbreak is required. The method we used for estimating the reproductive number is straightforward to implement and can be used in real-time. It therefore can be a useful tool to inform policy decisions.
Funding: This work was supported by research funding from the UK Department for Environment, Food and Rural Affairs. The views expressed in the paper are those of the authors.
Competing interests: The authors have declared that no competing interests exist.
Academic Editor: Enrico Scalas, University of East Piedmont, Italy
Citation: Garske T, Clarke P, Ghani AC (2007) The Transmissibility of Highly Pathogenic Avian Influenza in Commercial Poultry in Industrialised Countries. PLoS ONE 2(4): e349. doi:10.1371/journal.pone.0000349
Received: February 6, 2007; Accepted: March 14, 2007; Published: April 4, 2007
Copyright: ? 2007 Garske et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
* To whom correspondence should be addressed. E-mail: t.garske@imperial.ac.uk
http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0000349