CONTROL OF BOVINE VIRUS DIARRHEA - REVIEW ARTICLE

Possibilities of the control of bovine virus diarrhoea (BVD) have been summarized dealing partly with the prevention and treatment of the di sease and partly with the possibilities of eradication. Control is bas ed on the one hand on the prevention of introduction of the virus and on the other hand, on the detection and elimination of persistently in fected animals, prevention of transient and persistent infections by v accination and hygienic measures, as well as on the prevention of the enrichment of the causative agent on the farm. Introduction happens mo st frequently by persistently infected, temporarily viraemic animals, as well as by animals after viraemia still shedding the virus, by cont aminated live virus vaccines or biological materials of bovine origin. To prevent introduction, it is advisable to carry out the virus detec tion on the original farm in case of each trading. Newly purchased ani mals should be kept in quarantine at least for four weeks before enter ing the stock and tested serologically twice at the beginning and at t he end of the quarantine period. For controlling BVD it is imperative to detect and eliminate persistently infected animals. These animals a re persistently viraemic shedding great amounts of virus constantly. P ossibilities of the detection and elimination of persistently infected animals, as well as that of the identification of a stock with such a nimals have been detailed. Of the tools of the specific control both l ive and inactivated vaccines are available, the advantages and disadva ntages of them have also been summarized, Immunization of calves shoul d be carried out at the age of 4 to 6 months and re-vaccination before the first service. Another key issue of the control is the prevention of intrauterine infection. One of its most effective method is the co rrect vaccination of breeding animals 4 to 5 weeks before insemination and a yearly booster vaccination 3 to 5 weeks before calving. Norther n European experiences of the eradication have been reported in the se cond part of the article. Experiences obtained by the eradication meth ods used in Sweden, Norway, Finland and Denmark have been summarized. Stocks with an active infection should be detected for the eradication of the disease, the virus shedding animals should be eliminated and a dministrative rules should be introduced in all the stocks to prevent the infection of free stocks. The Hungarian experiences have shown tha t BVD could be eradicated in the Hungarian stocks by the adaptation of the Danish method.