EN
The first clinical cases of Schmallenberg virus infection diagnosed in a dead calf and five aborted lambs from flocks in north-western Poland between November 2012 and January 2013 are described. An epizootic investigation made it possible to determine that an SBV infection, which resulted in the first clinical case in the cattle herd from the West Pomerania, probably occurred in the spring of 2012. In most cases the presence of viral RNA was confirmed in the brain, cerebellum, medulla and spleen of animals. All mothers of SBV infected neonates had specific antibodies. Arthrogryposis and cartridge deformations, brachygnathia inferior, kyphosis and torticollis were the most common defects. Macroscopic changes of the cranial region included hydranencephaly, porencephaly, hypoplasia to atrophy of hindbrain. Histopathological examination of brain tissue revealed vacuolation and hypoplasia of neuropil and the presence of lymphohistiocytic perivascular infiltration, hypereosinophilic, necrotic neurons and microglial nodules. Focal hypoplasia to atrophy of white matter and mild hypoplasia of the gray matter was also observed.