H5N1 Bird Flu Could Be Controlled by Disinfection09 May 2013
VIET NAM - The implementation of thorough, daily disinfection of the market environment as well as of traders’ vehicles and equipment in only a small number of hubs can disconnect the network dramatically, preventing the spread of influenza A(H5N1), according to a new study. This would allow live bird markets to re-open without risking viral spread.
Highly pathogenic avian influenza virus subtype H5N1 is endemic in Asia, with live bird trade as a major disease transmission pathway.
Guillaume Fournié of the UK's Royal Veterinary College and co-authors in France, the UK and Viet Nam report in Proceedings of the National Academy of Sciences of the United States of America (PNAS) that the implementation of thorough, daily disinfection of the market environment as well as of traders’ vehicles and equipment in only a small number of hubs can disconnect the network dramatically, preventing disease spread.
These targeted interventions would be an effective alternative to the current policy of a complete ban of live bird markets in some areas, they concluded.
Some live bird markets that have been banned still are very active, and they likely have a substantial impact on disease dynamics, exhibiting the highest levels of susceptibility and infectiousness, according to the researchers.
Fournié and co-authors undertook a cross-sectional survey in northern Viet Nam to investigate the structure of the live bird market contact network and the implications for virus spread. Based on the movements of traders between live bird markets, weighted and directed networks were constructed and used for social network analysis and individual-based modeling.
They found that most live bird markets were connected to one another, suggesting that the live bird market network may support large-scale disease spread. Because of cross-border trade, it also may promote transboundary virus circulation. However, opportunities for disease control do exist, they said.
The number of trader visits to markets, information that can be collected quickly and easily, may be used to identify live bird markets suitable for implementing interventions. This would not require prior knowledge of the force of infection, for which laboratory-confirmed surveillance would be necessary.
The researchers added that their findings are of particular relevance for policy development in resource-scarce settings.
Fournié G., J. Guitian, S. Desvaux, V.C. Cuong, D.H. Dung, D.U. Pfeiffer, P. Mangtanie and A.C. Ghani. 2013. Interventions for avian influenza A (H5N1) risk management in live bird market networks. PNSA. Published online before print 6 May 2013. doi: 10.1073/pnas.1220815110
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