Seroprevalence and spatial distribution of maedi-visna virus and pestiviruses in Catalonia (Spain)

During the period 2004–2005 a serological survey was conducted in sheep flocks in Catalonia (North-Eastern Spain) in order to determine the seroprevalence of maedi-visna virus (MVV) and pestiviruses, such as Border Disease Virus (BDV), to investigate their spatial distribution and to obtain information about associations between them for planning and prioritizing the control measures in this region. A random sample of 241 sheep flocks stratified by counties was analyzed. A total of 5120 and 3611 animals were tested using different indirect ELISA methods for MVV and pestiviruses, respectively. The results showed that MVV and pestiviruses were very widespread in Catalonia. Ninety percent of sheep flocks were positive for MVV and sixty four percent were positive for Pestivirus genus. The spatial distributions of both viral pathogens were not homogenous: MVV seroprevalence within flock was higher in North-Western and Western Catalonia, whereas the antibody proportion of pestiviruses at the flock-level and within flock was higher in North-Western Catalonia. Large flocks had higher seroprevalences within flock than smaller ones. Mixed flocks showed higher risk of MVV infection than purely sheep flocks and there was a statistical association between MVV and pestivirus seroprevalence.