1995 Volume 48 Issue 9 Pages 646-649
During a period from autumn 1992 to through summer 1993 in the North-Eastern Chiba Prefecture, appeared a syndrome characterized by respiratory disorders in 1-to 5-month old piglets, and anorexia and fever in sows with abortion, and delivery of stillborne, mummified, premature or weakborne piglets. From the affected pigs on 8 farms, viral agents were isolated on swine alveolar macrophage cultures and identified as porcine reproductive and respiratory syndrome (PRRS) virus. The antigenicity of the virus was closely related to that of the American PRRS virus. The retrospective antibody survey of the virus by indirect immunofluorescence revealed an epizootic in this area in 1988.