From May 2013 to April 2014, 15 swine family-run farms (17 pig litters) in two districts in Hung Yen province, near Hanoi, were virologically and epizootiologically monitored for swine influenza viruses (SIV) monthly. No SIV was isolated from nasal swabs. Maternal antibodies were detected in 10 litters, and seroconversion against SIV was detected in six litters. There was a marked difference in patterns of SIV transmission in the two districts. Van Lam district which has low density of swine with mainly smallholder farms had low intensity of SIV, with much of the infection caused by H1N1 2009 pandemic-like viruses A(H1N1)pdm09, likely originated from humans. In contrast, Van Giang district, which has high swine density and larger farms, had high levels of typical SIV (triple reassortants H3N2 and H3N2 Binh Duong lineage viruses) circulating within swine. With one exception, the SIV lineages detected were those we concurrently isolated from studies in a large central abattoir in Hanoi. Influenza-like illness symptoms reported by farmers were poorly correlated with serological evidence of SIV infection.

中文翻译：

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2013年至2014年，越南北部的宏安省前哨家庭农场的猪流感病毒监测。

从2013年5月至2014年4月，每月对河内附近的兴安省两个地区的15个家庭经营的猪场（17个猪窝）进行病毒学和流行病学监测，以监测猪流感病毒（SIV）。没有从鼻拭子中分离出SIV。在10胎中检测到母体抗体，在6胎中检测到针对SIV的血清转化。在两个地区，SIV传播方式存在明显差异。范林区的猪密度较低，主要是小农户，SIV强度很低，大部分感染是由2009年H1N1大流行性病毒A（H1N1）pdm09引起的，很可能源于人类。相比之下，养猪密度高，农场规模大的Van Giang地区，猪中有高水平的典型SIV（三重配体H3N2和H3N2平阳谱系病毒）。除了一个例外，检测到的SIV谱系是我们同时从河内一个大型中央屠场的研究中分离出来的谱系。农民报告的流感样疾病症状与SIV感染的血清学证据相关性很低。