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nounmass nounVeterinary Medicine
A fatal disease of sheep in which there is progressive demyelination of neurons in the brain and spinal cord, caused by the maedi virus.‘It is a voluntary scheme with over 2800 flocks that have been blood tested and are accredited free of Maedi visna.’‘We conclude that sheep sera have a visna virus inhibiting factor and hypothesise that VIF inhibits early spread of visna virus in inoculated sheep and may be involved in initiating the persistent infection.’
1950s from Old Norse, ‘to wither’.
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