Histopathological changes of the brain in swine fetuses naturally infected with procine parvovirus

During a period from 1971 to 1972, some cases of stillbirth and abortion associated with porcine parvovirus infection were recognized in swine herds in Japan. The brain was examined histopathologically in five stillborn piglets and four dead fetuses from which the parvoviruses had been isolated. Similar histological changes were observed in all the piglets and fetuses, except one piglet which was free from recognizable lesions. The brain lesions were considered to belong to the category of meningoencephalitis consisting of perivascular cuffing of proliferating adventitial cells and a few plasma cells. They were localized in the cerebral gray and white matter and leptomeninges, but not in the cerebellum. These histological lesions were thought to be pathognomonic to porcine parvovirus infection. The difference in brain lesions between porcine parvovirus infection and Japanese encephalitis virus infection was discussed.