Ovine enzootic abortion: seroprevalence in Switzerland using a competitive enzyme linked immunosorbent assay (cELISA)

The present study gives an overview over the seroprevalence of ovine enzootic abortion in Switzerland. 639 sheep flocks out of eight cantons in Switzerland were examined by a competitive enzyme linked immunosorbent assay (cELISA) for antibodies against Chlamydophila abortus (Chlamydia psittaci serotype 1), the agent causing ovine enzootic abortion. The eight cantons included Aargau, Bern, Zurich, Appenzell-Ausserrhoden, Appenzell-Innerrhoden and Fribourg, the Vallais and the Graubunden. They were representative for 57% of the Swiss sheep flocks and for 60% of Swiss sheep population. In total, almost 19% (118) of the examined flocks were seropositive. Seroprevalence was the highest in Graubunden with 41%; this requires further examination and the evaluation of the need for a monitoring and controlling program. The examination of pooled. sera made it possible to test a large number of samples with a reasonable amount of work. Higher sensitivity (92.9%) and specifity (97.6%) than the complement fixation test (CFT) in combination with testing of pooled sera makes the cELISA to be an usuable tool for serological screening on flock level.