Campylobacter fetus fetus abortions in vaccinated ewes

Aims: To investigate the cause of an outbreak of ovine abortion in 1996 in a flock of 300 two-tooth (rising a-year-old) ewes vaccinated against Campyl obacter fetus fetus infection and to subsequently characterise the strain o f C. fetus fetus isolated from aborted foetuses. Methods: Standard bacteriological methods were used to identify C. fetus fe tus isolates which were then antigenically typed and subjected to pulsed-fi eld gel electrophoresis (PFGE) and compared to the vaccine strain. Results: C. fetus fetus was identified as the causal agent of the abortions despite the ewes having been vaccinated before ram introduction and at the time of ram removal. Four isolates cultured from aborted material were ind istinguishable when compared using antigenic typing and PFGE, but all diffe red from the vaccine strain. Conclusions: Within the limitations of the available typing systems, it is proposed that PFGE may be a useful tool to establish the distribution and s train variation of C. fetus fetus. Clinical relevance: This field case indicates the need for further study of non-vaccine C. fetus fetus strains which cause abortion in vaccinated ewes , and of the importance of these strains to the New Zealand sheep industry.