Abstract
A study was conducted in 1994–96 with the aim of assessing the serological prevalence of Border Disease (BD) among sheep and goats in Denmark and to investigate possible relations to herd factors. From each of 1000 herds, 2 blood samples were obtained from animals older than 1 year. The examination for antibodies was performed using a blocking ELISA detecting antibodies to pestivirus. Data from 815 herds were analysed statistically by the maximum likelihood method in a multinomial model. The estimated herd prevalence was 0.083 and the estimated individual prevalence within the positive herds was 0.50. There was no difference between the prevalence in sheep and goat herds. Records for well over half of the herds could be combined with data from the Danish Central Husbandry Register. No association between occurrence of BD and herd size was found. Cattle were registered as contemporarily present on 135 out of 521 herds – which was shown to be strongly associated to BD. The estimated herd prevalences of BD among farms with and without contemporary cattle were 0.24 and 0.042, respectively.
Keywords: pestivirus, serology, border disease virus, bovine virus diarrhoea, herd prevalence, individual prevalence, register data, maximum likelihood
Sammendrag
En undersøgelse udførtes i 1994–96 med det formål at bestemme den serologiske prævalens af Border disease (BD) blandt fåre- og gedebesætninger i Danmark, samt at belyse mulige sammenhænge med forskellige besætningsfaktorer. Fra 1000 besætninger blev der udtaget to blodprøver af dyr, som var ældre end 1 år. Undersøgelse for antistoffer blev foretaget ved blokerings-ELISA. Data blev analyseret statistisk ved hjælp af maksimum likelihood metoden i en multinomialfordeling. Den estimerede besætningsprævalens var 0.083, og den individuelle prævalens proportion i positive besætninger blev estimeret til 0.50. Der kunne ikke påvises nogen forskel på fåreog gedebesætninger.
For godt halvdelen af besætningerne kunne data kombineres med et udtræk fra CHR-registeret. Der kunne ikke vises nogen sammenhæng mellem forekomst af BD og besætningsstørrelse. Samtidigt kvæghold i besætningen var registreret på 135 ud af 521 besætninger, og data tydede på en klar sammenhæng mellem kvæghold og forekomst af BD. Den estimerede besætningsprævalens blandt besætninger med og uden kvæghold var henholdsvis 0.24 og 0.042.
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