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Diagnosis of toxoplasma abortion in ewes by polymerase chain reaction
  1. M. R. Owen, PhD, BSc, MRCVS1,
  2. M. J. Clarkson, PhD, DVSc, BSc, DSHP, MRCVS2 and
  3. A. J. Trees, PhD, BVM&S, MRCVS1
  1. 1 Department of Veterinary Parasitology, Liverpool School of Tropical Medicine/Faculty of Veterinary Science, University of Liverpool, Pembroke Place, Liverpool L3 SQA
  2. 2 Department of Veterinary Clinical Science and Animal Husbandry, Veterinary Teaching Hospital, University of Liverpool, Leahurst, Chester High Road, Neston, South Wirral L64 7TE


Eighteen oestrus-synchronised ewes were infected experimentally with 1500 sporulated oocysts of Toxoplasma gondii between 80 and 90 days of gestation. The infection induced pyrexia and specific antibody in all the ewes. One ewe resorbed its fetus, five ewes aborted and 12 delivered live, congenitally-infected lambs whose pre-colostral serum was antibody-positive. Tissues from the aborted fetuses and placentae from the live lambs were examined for toxoplasma infection by polymerase chain reaction (PCR) amplification of the Bi gene and by mouse inoculation. Using a simple protocol of tissue preparation without DNA extraction and a nested format, PCR was as sensitive as mouse inoculation. Placental cotyledon gave a higher sensitivity of detection than brain, lung or liver, and 16 of 19 placentae were positive by PCR compared with 13 of 18 by mouse inoculation. In mock-infected tissues, as few as 10 tachyzoites could be detected. The PCR could be applied to tissues unfit for mouse inoculation.

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