Evidence for transplacental and contact transmission of bluetongue virus in cattle
- F. D. Menzies, BVM&S, MSc, PhD, DipECVPH, MRCVS1,
- S. J. McCullough, BVSc, PhD, MRCVS2,
- I. M. McKeown, MVB, MSc, MRCVS1,
- J.L. Forster, BSc, MSc2,
- S. Jess, BSc, PhD3,
- C. Batten, BSc, PhD4,
- A. K. Murchie, BSc, PhD3,
- J. Gloster5,
- J. G. Fallows, BVM&S, MRCVS1,
- W. Pelgrim, DVM, BSA6,
- P. S. Mellor, BSc, MSc, PhD, DSc, FRES4 and
- C. A. L. Oura, BVetMed, MSc, PhD, MRCVS4
- 1 Department of Agriculture and Rural Development, Dundonald House, Upper Newtownards Road, Belfast BT4 3SB
- 2 Agri-Food and Biosciences Institute, Veterinary Sciences Division, Belfast BT4 3SD
- 3 Agri-Food and Biosciences Institute, Newforge Lane, Belfast BT9 5PX
- 4 Institute for Animal Health, Pirbright Laboratory, Ash Road, Woking, Surrey GU24 0NF
- 5 Met Office, Fitzroy Road, Exeter EX1 3PB
- 6 Ministry of Agriculture, Nature and Food Quality, Bezuidenhoutseweg 73, Postbus 20401, 2500 EK Den Haag, The Netherlands
- Mr Gloster's present address is Institute for Animal Health, Pirbright Laboratory, Ash Road, Woking, Surrey GU24 0NF
Abstract
This paper presents evidence that a field strain of bluetongue virus serotype 8 (btv-8) was transmitted transplacentally and that it was also spread by a direct contact route. Twenty pregnant heifers were imported from the Netherlands into Northern Ireland during the midge-free season. Tests before and after the animals were imported showed that eight of them had antibodies to bluetongue virus, but no viral rna was detected in any of them by reverse transcriptase-pcr (rt-pcr). Two of the seropositive heifers gave birth to three calves that showed evidence of bluetongue virus infection (rt-pcr-positive), and one of the calves was viraemic. Two further viraemic animals (one newly calved Dutch heifer, and one milking cow originally from Scotland) were also found to have been infected with btv-8 and evidence is presented that these two animals may have been infected by direct contact, possibly through the ingestion of placentas infected with btv-8.
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