Porcine epidemic diarrhea (PED) virus (PEDV) is a globally emerging and re-emerging epizootic swine virus that causes massive economic losses in the swine industry, with high mortality in piglets. In Vietnam, PED first emerged in 2009 and has now developed to an endemic stage. This is the first cross-sectional survey performed to evaluate the proportion of PEDV-positive swine farms in Vietnam from January 2018 to February 2019. Fecal samples from 327 pig farms in northern Vietnam were collected and tested for PEDV infection by reverse transcription-loop-mediated isothermal amplification (RT-LAMP) method. The proportion of PEDV-positive farms was 30.9% and PEDV-positive farms were distributed throughout the study area. The highest proportion of PEDV-positive farms was 70% (7/10) among nucleus production type farms (P < 0.05). Higher proportions of PEDV-positive farms were found in the Northeast and Red River Delta areas, which are the major areas of pig production (P < 0.05). The proportion of PEDV-positive farms was higher among larger farms (P < 0.05). Our findings illustrate the high proportion of PEDV-positive farms in the Vietnamese pig population and will help to better understand the epidemiological dynamics of PED infection, to estimate impact, and establish and improve prevention and control measures.

猪流行性腹泻（PED）病毒（PEDV）是一种全球新兴和重新出现的流行性猪病毒，在养猪业中造成巨大的经济损失，仔猪死亡率很高。在越南，PED于2009年首次出现，现已发展到流行阶段。这是首次评估越南2018年1月至2019年2月PEDV阳性猪场所占比例的横断面调查。收集了越南北部327个猪场的粪便样本，并通过逆转录-定量环化法检测了PEDV感染情况介导的等温扩增（RT-LAMP）方法。PEDV阳性农场的比例为30.9％，PEDV阳性农场分布在整个研究区域。在有核生产型农场中，PEDV阳性农场的比例最高，为70％（7/10）（P <0.05）。在东北和红河三角洲地区发现的PEDV阳性猪场比例较高，这是养猪生产的主要地区（P  <0.05）。大农场中PEDV阳性农场的比例更高（P  <0.05）。我们的发现说明越南猪种群中PEDV阳性农场的比例很高，将有助于更好地了解PED感染的流行病学动态，估计影响并建立和改进预防和控制措施。