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Extract Johne's disease of sheep in New Zealand was first described by Williamson and Salisbury (1952 Williamson, G. T. and Salisbury, R. M. 1952. N.Z. vet. J., 1: 15–15. [Taylor & Francis Online] , [Google Scholar]) after the diagnosis had been confirmed in a sheep flock in the Hunter district of South Canterbury. Since that occasion the disease has been diagnosed and confirmed in 13 more sheep flocks in South Canterbury and 2 flocks in the Ashburton County adjacent to the northern boundary of South Canterbury.
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M. C. Armstrong (1956) studied this question.
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