Baudon Eugénie, Peyre Marisa, Peiris Malik, Cowling Benjamin John
WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Animal and Integrated Risk Management Research Unit (AGIRs), French Agricultural Research Center for International Development (CIRAD), Montpellier, France.
PLoS One. 2017 Jun 7;12(6):e0179044. doi: 10.1371/journal.pone.0179044. eCollection 2017.
The emergence of the 2009 influenza pandemic virus with a swine origin stressed the importance of improving influenza surveillance in swine populations. The objectives of this systematic review and meta-analysis were to describe epidemiological features of swine influenza (SI) across the world and identify factors impacting swine influenza virus surveillance.
The systematic review followed the PRISMA guidelines. Articles published after 1990 containing data on SI on pig and herd-level seroprevalence, isolation and detection rates, and risk factors were included. Meta-regression analyses using seroprevalence and virological rates were performed.
A total of 217 articles were included. Low avian influenza (AI) seroprevalence (means pig = 4.1%; herd = 15%) was found, showing that AIV do not readily establish themselves in swine while SIV seroprevalence was usually high across continents (influenza A means pig = 32.6-87.8%; herd = 29.3-100%). Higher pig density and number of pigs per farm were shown by the meta-regression analyses and/or the risk factor articles to be associated with higher SI seroprevalence. Lower seroprevalence levels were observed for countries with low-to-medium GDP. These results suggest that larger industrial farms could be more at risk of SIV circulation. Sampling swine with influenza-like illness (ILI) was positively associated with higher isolation rates; most studies in Europe, Latin and North America were targeting swine with ILI.
To improve understanding of SI epidemiology, standardization of the design and reporting of SI epidemiological studies is desirable. Performance of SI surveillance systems in low-to-medium GDP countries should be evaluated to rule out technical issues linked to lower observed SIV prevalence. Targeting certain swine age groups, farming systems and swine with ILI may improve the surveillance cost-effectiveness. However, focusing on pigs with ILI may bias virus detection against strains less virulent for swine but which may be important as pandemic threats.
2009年源自猪的甲型流感大流行病毒的出现凸显了加强猪群流感监测的重要性。本系统评价和荟萃分析的目的是描述全球猪流感（SI）的流行病学特征，并确定影响猪流感病毒监测的因素。
本系统评价遵循PRISMA指南。纳入1990年后发表的包含猪和猪群水平血清阳性率、分离率和检出率以及危险因素等猪流感数据的文章。使用血清阳性率和病毒学率进行荟萃回归分析。
共纳入217篇文章。发现禽流感（AI）血清阳性率较低（猪平均为4.1%；猪群为15%），表明禽流感病毒不易在猪群中立足，而猪流感病毒血清阳性率在各大洲通常较高（甲型流感猪平均为32.6 - 87.8%；猪群为29.3 - 100%）。荟萃回归分析和/或危险因素文章显示，较高的猪密度和每个农场的猪数量与较高的猪流感血清阳性率相关。中低GDP国家的血清阳性率水平较低。这些结果表明，较大的工业化农场可能更易发生猪流感病毒传播。对有流感样疾病（ILI）的猪进行采样与较高的分离率呈正相关；欧洲、拉丁美洲和北美的大多数研究针对的是有ILI的猪。
为更好地了解猪流感流行病学，猪流感流行病学研究的设计和报告标准化是可取的。应评估中低GDP国家猪流感监测系统的性能，以排除与观察到的较低猪流感病毒流行率相关的技术问题。针对某些猪龄组、养殖系统和有ILI的猪可能会提高监测的成本效益。然而，专注于有ILI的猪可能会使病毒检测偏向对猪毒性较低但可能作为大流行威胁很重要的毒株。
