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Trypanosoma melophagium from the sheep ked Melophagus ovinus on the island of St Kilda

  • W. GIBSON (a1), J. G. PILKINGTON (a2) and J. M. PEMBERTON (a2)

Summary

The sheep ked has been largely eradicated in the UK but persists in the feral Soay sheep of St Kilda in the Outer Hebrides. Sheep keds transmit Trypanosoma melophagium, but parasitaemias are typically cryptic and this trypanosome has not been recorded in the St Kilda sheep. Trypanosomes were detected by PCR in preserved keds and were also found in gut smears from live keds; one infected gut was used to establish the trypanosome in vitro. Examination of the morphology of bloodstream forms from culture confirmed its identity as T. melophagium. Most keds were found to harbour the trypanosome, particularly those collected from lambs. DNA was extracted from preserved keds and from trypanosomes grown in vitro. Sequence analysis of the small subunit ribosomal RNA (SSU rRNA) gene and the spliced leader transcript showed the T. melophagium sequences to be very similar to those from T. theileri. A partial sequence of the ked SSU rRNA gene was also obtained. The close genetic relationship of T. melophagium and T. theileri suggests that T. melophagium represents a lineage of T. theileri that adapted to transmission by sheep keds and hence became a specific parasite of sheep.

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Corresponding author

*Corresponding author: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK. Tel: 0117 928 8249. Fax: 0117 331 7985. E-mail: w.gibson@bris. ac.uk

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Keywords

Trypanosoma melophagium from the sheep ked Melophagus ovinus on the island of St Kilda

  • W. GIBSON (a1), J. G. PILKINGTON (a2) and J. M. PEMBERTON (a2)

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