由于自然免疫力下降 猪流行性腹泻传染（PED）风险增加

　　US - The executive director of the US based Swine Health Information Center warns, as natural immunity to Porcine Epidemic Diarrhea, resulting from previous exposure dissipates, the risk of the virus spreading will increase, writes Bruce Cochrane.Since peaking in March 2014, there's been a steady decline in the number of farms in the United States infected by Porcine Epidemic Diarrhea.Dr Paul Sundberg, the executive director of the Swine Health Information Center, says one of the reason is that as the virus went through the production units in the US it did cause infection and that causes a natural level of immunity so we have less susceptible animals

　　布鲁斯·科克伦(Bruce Cochrane)写道，基于猪健康信息中心执行理事的警告，由于先前的自然免疫力下降，猪流行性腹泻传染的风险增加。自从2014年3月感染高峰开始，在美国受到猪流行性腹泻病感染的农场数量在稳步下降。猪健康信息中心的执行理事保罗•桑德博格(Paul Sundberg)博士称，其中一个原因就是病毒通过美国的生产设备时引发感染，因为有一层自然免疫，以至于我们的动物不易受到感染。