Department of Population Medicine, University of Guelph, Guelph, ON, Canada.
Department of Pathobiology, University of Guelph, Guelph, ON, Canada.
Transbound Emerg Dis. 2018 Feb;65(1):e145-e154. doi: 10.1111/tbed.12701. Epub 2017 Sep 22.
The objective of this study was to investigate the association between environmental temperature and humidity and the presence of antibodies for two specific strains of swine influenza viruses: A/SW/ON/105-56/12/H3N2 (H3N2_D) and A/SW/ON/84/2012/H1N1 (H1N1_P). A cross-sectional study was performed in a commercial farm, and a total of 450 pigs at 10 weeks of age were blood sampled, by sampling 10 pigs per week for 45 weeks corresponding to 45 batches. Exposure of pigs to H3N2_D and H1N1_P virus was assessed by haemagglutination inhibition assay (HI), and a result of ≥1:40 was considered as indication of a positive exposure status for a specific strain. The selection of those two viruses was based on the fact that H1N1 was the dominant virus in Ontario herds, and H3N2 had been previously isolated in this particular farm. Environmental conditions were recorded through a portable device every 5 min and then summarized using descriptive statistics. The association between HI titres and environmental microconditions, in the nursery, was evaluated through random effect linear and logistic regression. The results showed that the prevalence for H1N1_P was high throughout the study (≥70%); however, for H3N2_D, the seroprevalence declined by the end of the study period. Results also showed an association between cumulative exposure to the viruses and temperature and relative humidity (p < .05). These results suggest that microclimate conditions can influence transmission patterns of influenza viruses in swine barns, and that even a herd with relatively simple demographics could have persistent and cocirculation of two different influenza A viruses IAV strains.
A/SW/ON/105-56/12/H3N2（H3N2_D）和 A/SW/ON/84/2012/H1N1（H1N1_P）。本研究采用横断面研究方法，在一个商业农场中进行，共采集了 450 头 10 周龄的猪血液样本，每周采集 10 头猪，共采集 45 周，对应 45 批。通过血凝抑制试验（HI）评估猪对 H3N2_D 和 H1N1_P 病毒的暴露情况，结果≥1:40 被认为是特定毒株阳性暴露状态的指标。选择这两种病毒是基于以下事实：H1N1 是安大略省畜群中的优势病毒，而 H3N2 曾在该特定农场中分离到。通过便携式设备每 5 分钟记录一次环境条件，并使用描述性统计方法进行总结。通过随机效应线性和逻辑回归评估了保育舍中 HI 滴度与环境微环境之间的关系。结果表明，整个研究期间 H1N1_P 的流行率较高（≥70%）；然而，对于 H3N2_D，血清阳性率在研究期末下降。结果还表明，病毒的累积暴露与温度和相对湿度之间存在关联（p<.05）。这些结果表明，小气候条件可能会影响猪舍中流感病毒的传播模式，即使是一个具有相对简单人口统计学特征的畜群，也可能存在两种不同的甲型流感病毒 IAV 株的持续和共同循环。
