Seroprevalence of bovine viral diarrhoea virus in Hungary - situation before launching an eradication campaign.

Bovine viral diarrhoea (BVD) is a viral disease appearing in various forms and causing high economic losses in the cattle stocks of Hungary. The aim of the present study was to determine the prevalence of bovine viral diarrhoea virus (BVDV) in Hungary through a monitoring survey carried out on samples collected in cattle-keeping units throughout the country. Since no such survey had been carried out in Hungary during the last thirty years, our study may serve as a basis for later monitoring investigations aimed at following the progress of an expected eradication campaign of BVD. The tests were carried out using an ELISA method, on a total of 1200 blood samples submitted from 54 cattle herds. The herds had not been vaccinated against BVDV before the sampling. Out of the 1200 samples, 521 proved to be positive (43.4%), 40 gave doubtful result (3.3%) and 639 were negative (53.3%). In some stocks the samples were collected from cows having completed several lactation periods, and therefore the seronegativity indicates the BVDV-free status of the given stock. Moreover, among the positive herds we found a few where the seropositivity rate was rather low (< 5%). According to the results of the survey, a rather high portion (about one third) of the cattle-keeping units of Hungary can be regarded as BVDV free, which ratio is much higher than had been expected on the basis of surveys carried out on a lower number of samples and in smaller regions of the country. Hence, the chances of an eradication campaign launched in the near future, or carried out parallel to the IBR eradication programme, are better than previously expected.