EN
Six consecutive enzooties of SVD in the years of 1973/1978 were described. The first enzooty involved almost the total number of pigs on a farm (approximately 3500 animals). In 8.4 per cent the disease many abortions at different stages of pregnancy were noted. Out of 296 pigs with nervous symptoms of the disease, 122 animals were treated by sedative drugs and cardiatic ones. In the cured group of animals, 53.3 per cent recovered compared with only one pig with the symptoms of cahexia out of 174 control animals. In the recovered animals the titres of seroneutralizing antibodies ranged from 80 to 160 through out the year. The same titres of antibodies were noted in piglets coming from convalescent sows. The convalescent pigs were resistant to natural and artificial infections with SVDV. The consecutive enzooties with SVDV were of mild course without nervous symptoms of the disease and concerned 0.3-1.0 per cent of pigs; no animal died.