A fatal disease of sheep in which there is progressive demyelination of neurons in the brain and spinal cord, caused by a 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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