SEROEPIDEMIOLOGICAL SURVEY OF BORDER DISEASE (BD) IN SYRIAN AWASSI SHEEP

A seroepidemiologic survey was conducted in all provinces of the Syria n Arab Republic to determine prevalence of antibodies against Border D isease (ED) virus in Awassi sheep flocks. About 45% of the animals wer e positive (IIF method). Northwest provinces showed highest percentage of seropositive animals (up to 94%), while ED was almost absent in th e southern provinces. Distribution of anti-ED antibodies appeared to b e related to two aspects of flock management, distance of transhumance and the use and quality of pens. The higher prevalence in long distan ce transhumant flocks is possibly related to the higher risk of contac ts with persistently infected and virus excreting animals. Similarly, stress due to sheltering in poorly ventilated and humid folds may faci litate occurrence of the infection. Sheep from the wettest regions, wi th more than 600 mm of rainfall per year (IA zone), showed a higher pr evalence to ED, when compared to those from dry areas. This may be rel ated to the rapid inactivation of the virus by desiccation. Occurrence of ED infection was related to a mortality rate up to 20% of lambs.