Monitoring studies of bluetongue disease in ruminants imported to Poland from EU

The results of 4-year serological and 2-year virological monitoring studies of bluetongue (BT) disease in ruminants imported to Poland from EU countries are presented. Sera were screened using the c-ELISA and direct ELISA tests. Out of 49587 samples of sea, 3385 (6.83% of a total number of samples) were found to be positive for bluetongue virus (BTV). The majority of seropositive animals were imported to Poland from Germany, Czech Republic and The Netherlands. The high number of positive animals detected in 2008-2009 was the result of bluetongue vaccination implemented in BTV-infected EU countries in 2008. The rRT-PCR was applied to detect viral RNA in blood samples. The presence of BTV RNA was found in 38 samples of blood collected from German cows, one sample from Dutch fallow deer and one sample from a 4-week-old calf born from BT positive dam imported from Germany. On the basis of present results it can be stated that the implemented virological surveillance investigations should be continued to monitor the actual BT status in Poland. As it is impossible to differentiate infected from vaccinated animals and deduce whether the animals have been or have not been vaccinated properly, the continuation of serological monitoring studies using actually available ELISA kits should be reconsidered.