关键词: 猪蓝耳病； 野毒感染； 返饲； 经济学

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