AN OUTBREAK OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME IN JAPAN

An emerging swine disease principally involving periweaning piglets wa s examined. The disease was clinically characterized by lethargy, feve r, emaciation, coughing, and severe abdominal breathing, hence colloqu ially named ''Heko-heko'' disease. The consistent lesions in affected piglets were diffuse interstitial pneumonia with pronounced type II pn eumocytic proliferation, meningoencephalitis, and regression of the ly mphoid tissues. The causal virus was isolated in primary porcine lung cell (PLC) cultures from various organs of affected piglets and showed serological relatedness to the European porcine reproductive and resp iratory syndrome (PRRS) virus. Numerous virus particles, measured abou t 49 nm in diameter, were detected in the cytoplasm of alveolar epithe lial cells and pulmonary macrophages in PLC cultures infected with the isolate. The condition could be experimentally reproduced in conventi onal piglets by intranasal inoculation with the isolate and the virus was reisolated from the infected animals.