Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa; Western Cape Department of Agriculture, Elsenburg, 7607, South Africa.
Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa.
Prev Vet Med. 2021 Nov;196:105474. doi: 10.1016/j.prevetmed.2021.105474. Epub 2021 Aug 26.
High pathogenicity avian influenza (HPAI) has become a major focus point worldwide due to its zoonotic potential and economic effects resulting from trade restrictions and high mortality rates in poultry. Key ostrich producing provinces of South Africa have experienced three H5N2 HPAI outbreaks (2004, 2006 and 2011) and one H5N8 HPAI (2017) outbreak over the past two decades. The Klein Karoo region in the Western Cape Province, a province with a largely Mediterranean climate, is the predominant ostrich producing region in the country. Understanding the epidemiology of HPAI in ostrich producing areas is an essential first step in developing effective and efficient control measures. This study investigated the spatiotemporal patterns associated with the 2011 (H5N2) and 2017 (H5N8) HPAI outbreaks in the key ostrich producing areas of South Africa. Six hundred and nine and 340 active ostrich farms/holdings were subjected to surveillance during 2011 and 2017 respectively, with over 70 % of these farms located within five local municipalities of the study area. Forty-two and fifty-one farms were affected in the 2011 and 2017 outbreaks respectively. Both HPAI outbreaks occurred predominantly in areas of high ostrich farm density. However, the temporal occurrence, spatial and directional distributions of the outbreaks were different. The 2011 outbreak occurred earlier in the South African autumn months with a predominantly contiguous and stationary distribution, whilst the 2017 outbreak onset was during the winter with a more expansive multidirectional spatial distribution. Results suggest potential dissimilarities in the important risk factors for introduction and possible mode of spread. The 2011 outbreak pattern resembled an outbreak characterised by point introductions with the risk of introduction possibly being linked to high ostrich farm density and common management and husbandry practices in the ostrich industry. In contrast, the 2017 outbreak appeared to have a more propagating mode of transmission. The findings highlight epidemiological features of HPAI outbreak occurrence within ostrich populations that could be used to inform surveillance and control measures including targeted surveillance within high-risk spatial clusters. The study emphasizes the importance of both; implementation of a multi-pronged approach to HPAI control and the need for constant evaluation of the interaction of the host, environment and agent with each outbreak, in order to strengthen disease control.
高致病性禽流感（HPAI）因其人畜共患潜力以及贸易限制和家禽高死亡率带来的经济影响而成为全球关注的焦点。南非主要的鸵鸟生产省份在过去二十年中经历了三次 H5N2 高致病性禽流感（2004 年、2006 年和 2011 年）和一次 H5N8 高致病性禽流感（2017 年）爆发。西开普省的克林卡鲁地区，气候主要为地中海气候，是该国主要的鸵鸟生产地区。了解鸵鸟生产地区高致病性禽流感的流行病学是制定有效和高效控制措施的第一步。本研究调查了 2011 年（H5N2）和 2017 年（H5N8）高致病性禽流感在南非主要鸵鸟生产地区的时空模式。2011 年和 2017 年分别对 609 家和 340 家活跃的鸵鸟养殖场/养殖场进行了监测，其中超过 70%的养殖场位于研究区域的五个地方自治市。2011 年和 2017 年的爆发分别有 42 家和 51 家农场受到影响。两次高致病性禽流感爆发都主要发生在高鸵鸟养殖场密度的地区。然而，疫情的时间发生、空间和方向分布不同。2011 年的疫情发生在南非秋季的早期，呈连续和静止的分布，而 2017 年的疫情发生在冬季，呈更广泛的多向空间分布。结果表明，传入的重要风险因素和可能的传播方式可能存在差异。2011 年的疫情模式类似于以点状传入为特征的疫情，传入的风险可能与高鸵鸟养殖场密度以及鸵鸟产业中常见的管理和饲养实践有关。相比之下，2017 年的疫情似乎具有更具传播性的传播模式。研究结果突出了高致病性禽流感在鸵鸟种群中的爆发发生的流行病学特征，这些特征可用于为监测和控制措施提供信息，包括在高风险空间集群内进行有针对性的监测。该研究强调了实施多管齐下的高致病性禽流感控制方法的重要性，以及不断评估宿主、环境和病原体相互作用的必要性，以加强疾病控制。
