|The 5 year old dairy cow came from a farm in Dielsdorf district (canton of Zurich) with 44 cows and showed no clinical/pathological signs.
The diagnosis was made at the Institute of Virology, Vetsuisse-Faculty, Veterinary Medicine, University of Zurich using ELISA (enzyme-linked immunosorbent assay).
The source of outbreak or origin of infection remained unknown or inconclusive.
Control measures undertaken were
quarantine - the farm has been banned from moving animals. Contact of quarantined animals with other animals is strictly forbidden. The ban
cannot be removed until all the cattle on the affected farm have tested negative on 2 different occasions at an interval of at least 90 days.
disinfection of premises - treatment of affected animals: no. Vaccination prohibited: yes.
For the following reasons it is questionable whether the cow in question represented a real EBL case:
a. The pathological examination (macroscopic and microscopic) revealed no
findings to indicate a potential presence of EBL.
b. The 3rd serological test done with a blood sample taken immediately before destruction of the cow in question yielded a doubtful result,
exactly as the first serological examination had done.
c. The epidemiological situation is not typical of EBL. The animal concerned was the only animal out of 42 that tested positive for EBL.
The national reference laboratory for EBL (Institute of Veterinary Virology, University of Bern) considers that the positive serology result
might have been a false positive.
Nevertheless, to be on the safe side, the case was treated as a real outbreak, in accordance with the relevant Swiss legislation, and all
precautionary measures were taken, including quarantine and disease notification to the OIE.
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