Royal Veterinary College, Veterinary Epidemiology & Public Health Group, Dpt Veterinary Clinical Sciences, Hawkshead Lane, North Mymms, Hatfield, Herts AL9 7TA, UK.
BMC Vet Res. 2010 Feb 22;6:10. doi: 10.1186/1746-6148-6-10.
The structure of contact between individuals plays an important role in the incursion and spread of contagious diseases in both human and animal populations. In the case of avian influenza, the movement of live birds is a well known risk factor for the geographic dissemination of the virus among poultry flocks. Live bird markets (LBM's) contribute to the epidemiology of avian influenza due to their demographic characteristics and the presence of HPAI H5N1 virus lineages. The relationship between poultry producers and live poultry traders (LPT's) that operate in LBM's has not been adequately documented in HPAI H5N1-affected SE Asian countries. The aims of this study were to document and study the flow of live poultry in a poultry trade network in northern Vietnam, and explore its potential role in the risk for HPAI H5N1 during 2003 to 2006.
Our results indicate that LPT's trading for less than a year and operating at retail markets are more likely to source poultry from flocks located in communes with a past history of HPAI H5N1 outbreaks during 2003 to 2006 than LPT's trading longer than a year and operating at wholesale markets. The results of the network analysis indicate that LPT's tend to link communes of similar infection status.
Our study provides evidence which can be used for informing policies aimed at encouraging more biosecure practices of LPT's operating at authorised LBM's. The results suggest that LPT's play a role in HPAI H5N1 transmission and may contribute to perpetuating HPAI H5N1 virus circulation amongst certain groups of communes. The impact of current disease prevention and control interventions could be enhanced by disseminating information about outbreak risk and the implementation of a formal data recording scheme at LBM's for all incoming and outgoing LPT's.
人与人之间的接触结构在人类和动物群体传染病的入侵和传播中起着重要作用。在禽流感的情况下，活禽的流动是病毒在禽群中地理传播的一个众所周知的风险因素。活禽市场（LBM）由于其人口特征和存在高致病性禽流感 H5N1 病毒谱系，对禽流感的流行病学做出了贡献。在受高致病性禽流感 H5N1 影响的东南亚国家，家禽生产者与在 LBM 中经营的活禽交易商（LPT）之间的关系没有得到充分记录。本研究的目的是记录和研究越南北部家禽贸易网络中活禽的流动，并探讨其在 2003 年至 2006 年期间感染高致病性禽流感 H5N1 的潜在风险。
我们的研究结果表明，经营时间少于一年且在零售市场交易的 LPT 更有可能从 2003 年至 2006 年曾有高致病性禽流感 H5N1 爆发史的社区的禽群中获取家禽，而经营时间超过一年且在批发市场交易的 LPT 则不然。网络分析的结果表明，LPT 倾向于将具有相似感染状况的社区联系起来。
我们的研究提供了证据，可以用于为旨在鼓励在授权的 LBM 中经营的 LPT 采取更具生物安全性的做法的政策提供信息。研究结果表明，LPT 在高致病性禽流感 H5N1 的传播中发挥了作用，并可能有助于在某些社区群体中持续传播高致病性禽流感 H5N1 病毒。通过在 LBM 为所有进出 LPT 传播有关疫情风险的信息并实施正式的数据记录计划，可以增强当前疾病预防和控制干预措施的效果。
