Abstract: The porcine PRRS virus mutates rapidly with multiple strains coexist. Vaccine protection effect for the virus is not ideal. At present，more and more breeding farms eradicate PRRS virus in the herd，but it is difficult to maintain the negative status. This paper reported a a PRRS JXA1?like strain outbreak in a PRRS ?negative breeding farms. Methods of emergency feedback，strengthening biosecurity，and increasing the health care were taken，and the herd was improved. Feedback and other measures can quickly control the disease. When the PRRS negative farm turns positive，veterinarians need to make decisions on prevention，control and eradication from an economic point of view and use the future income to convert to the net present value evaluation method，and the investment income ratio this time is 1: 3.3，indicating that the method of feedback at this time is economically feasible.

Key words: PRRS； Virus infection； Feedback； Economics

摘要： 猪蓝耳病病毒变异快，且多种毒株并存，疫苗保护效果差。当前越来越多的种猪场 完成了猪蓝耳病的净化工作，但净化后维持难度较大。该文报道猪蓝耳病阴性种猪场在日常 监测中发现感染猪蓝耳病JXA1?like野毒株，通过采用紧急返饲的方法，并强化猪场生物安全、 加强猪群中西药保健、提升猪群健康度等措施，能快速将本次发病控制下来。当猪蓝耳病阴性 场转阳后如何处置，兽医需从经济学的角度去做防控和净化的决策。采用未来收益折算为净 现值评估的方法，得出本次投入收益比为1∶3.3，说明本次通过返饲的处理方法是经济可行的。

关键词: 猪蓝耳病； 野毒感染； 返饲； 经济学