Meyer Anne, Dinh Tung Xuan, Nhu Thu Van, Pham Long Thanh, Newman Scott, Nguyen Thuy Thi Thanh, Pfeiffer Dirk Udo, Vergne Timothée
Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, United-Kingdom.
National Institute for Animal Sciences, Hanoi, Vietnam.
PLoS One. 2017 Jun 20;12(6):e0178241. doi: 10.1371/journal.pone.0178241. eCollection 2017.
Presence of ducks, and in particular of free-grazing ducks, has consistently been shown to be one of the most important risk factors for highly pathogenic avian influenza outbreaks which has compromised poultry production in South-East Asia since the early 2000s and continues to threaten public health, farmers' livelihood and food security. Although free-grazing duck production has been practised for decades in South-East Asia, there are few published studies describing this production system, which is suspected to play an important role in the maintenance of avian influenza viruses. This study aimed at describing quantitatively the long-distance free-grazing duck production system in South Vietnam, characterising the movement and contact patterns of the duck flocks, and identifying potential associations between farming practices, movement and contact patterns and the circulation of avian influenza viruses. We conducted interviews among stakeholders involved in the free-grazing duck production system (duck farmers, transporters and rice paddy owners) in combination with a virological cross-sectional survey in South Vietnam. Results show that both direct and indirect contacts between free-grazing duck flocks were frequent and diverse. The flocks were transported extensively across district and province boundaries, mainly by boat but also by truck or on foot. A third of the investigated flocks had a positive influenza A virology test, indicating current circulation of avian influenza viruses, but none were positive for H5 subtypes. The age and size of the flock as well as its location at the time of sampling were associated with the risk of influenza A circulation in the flocks. These findings should be considered when developing risk assessment models of influenza virus spread aimed at informing the development of improved biosecurity practices leading to enhanced animal health, sustainable animal production and reliable income for farmers.
鸭子的存在，尤其是自由放牧的鸭子，一直被证明是高致病性禽流感疫情最重要的风险因素之一。自21世纪初以来，高致病性禽流感疫情危及了东南亚的家禽生产，并继续威胁着公共卫生、农民生计和粮食安全。尽管自由放牧鸭养殖在东南亚已实行了数十年，但鲜有关于这种养殖系统的公开研究，而该系统被怀疑在禽流感病毒的传播中起着重要作用。本研究旨在定量描述越南南部的长途自由放牧鸭养殖系统，刻画鸭群的移动和接触模式，并确定养殖方式、移动和接触模式与禽流感病毒传播之间的潜在关联。我们对自由放牧鸭养殖系统的利益相关者（鸭农、运输商和稻田主）进行了访谈，并在越南南部开展了一项病毒学横断面调查。结果表明，自由放牧鸭群之间的直接和间接接触频繁且多样。鸭群广泛地跨区、跨省运输，主要通过船运，但也有通过卡车或徒步运输的。三分之一的被调查鸭群甲型流感病毒检测呈阳性，表明禽流感病毒正在传播，但均未检测出H5亚型呈阳性。鸭群的年龄、规模及其在采样时的位置与鸭群中甲型流感病毒传播的风险相关。在制定流感病毒传播风险评估模型时应考虑这些发现，以便为改进生物安全措施提供依据，从而促进动物健康、实现可持续的动物生产并为农民带来可靠收入。
