Infectious Disease Epidemiology Unit, School of Population Health, University of Queensland, Brisbane, Australia.
PLoS One. 2012;7(11):e49712. doi: 10.1371/journal.pone.0049712. Epub 2012 Nov 16.
The number of outbreaks of highly pathogenic avian influenza virus of the H5N1 subtype (HPAIV H5N1) over the past 5 years has been drastically reduced in China but sporadic infections in poultry and humans are still occurring. In this study, we aimed to investigate seasonal patterns in the association between the movement of live poultry originating from southern China and HPAIV H5N1 infection history in humans and poultry in China.
METHODOLOGY/PRINCIPAL FINDINGS: During January to April 2010, longitudinal questionnaire surveys were carried out monthly in four wholesale live bird markets (LBMs) in Hunan and Guangxi provinces of South China. Using social network analysis, we found an increase in the number of observed links and degree centrality between LBMs and poultry sources in February and March compared to the months of January and April. The association of some live poultry traders (LPT's) with a limited set of counties (within the catchment area of LBMs) in the months of February and March may support HPAIV H5N1 transmission and contribute to perpetuating HPAIV H5N1 virus circulation among certain groups of counties. The connectivity among counties experiencing human infection was significantly higher compared to counties without human infection for the months of January, March and April. Conversely, counties with poultry infections were found to be significantly less connected than counties without poultry infection for the month of February.
CONCLUSIONS/SIGNIFICANCE: Our results show that temporal variation in live poultry trade in Southern China around the Chinese New Year festivities is associated with higher HPAIV H5N1 infection risk in humans and poultry. This study has shown that capturing the dynamic nature of poultry trade networks in Southern China improves our ability to explain the spatiotemporal dissemination in avian influenza viruses in China.
过去 5 年来，中国 H5N1 亚型高致病性禽流感（HPAIV H5N1）疫情爆发的次数大幅减少，但家禽和人类仍有零星感染。本研究旨在调查中国南方活禽流动与人间和家禽 HPAIV H5N1 感染史之间季节性关联的模式。
方法/主要发现：2010 年 1 月至 4 月期间，我们在中国华南的湖南和广西两省的 4 个批发市场（LBM）每月进行一次纵向问卷调查。通过社会网络分析，我们发现与 1 月和 4 月相比，2 月和 3 月 LBM 与家禽来源之间的观察到的联系数量和中心度有所增加。一些活禽交易商（LPT）与 LBM 集水区内的有限数量的县（LBM 集水区内的县）在 2 月和 3 月保持关联，这可能支持 HPAIV H5N1 的传播，并有助于在某些县群体中持续存在 HPAIV H5N1 病毒循环。与没有人间感染的月份相比，在 1 月、3 月和 4 月，发生人间感染的县之间的连通性明显更高。相反，在 2 月，有家禽感染的县与没有家禽感染的县相比，连通性显著降低。
结论/意义：我们的研究结果表明，中国南方农历新年前后活禽贸易的时间变化与人间和家禽 HPAIV H5N1 感染风险增加相关。本研究表明，捕捉中国南方家禽贸易网络的动态特性提高了我们解释中国禽流感病毒时空传播的能力。
