21-04-2008 - Scrapie transmission via milk
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Scrapie transmission via milkAndrew Gresham1
1 DEFRA, Area E, Level 7, 9 Millbank, c/o Nobel House, 17 Smith Square, London SW1P 3JR
SIR, - Franscini and others (2006) reported that normal cellular prion protein (PrP) is present in milk from humans and ruminants. Konold and others (2008) also reported the transmission of scrapie infectivity using milk from sheep infected with classical scrapie, although they commented that the possibility of the transmission of scrapie from the ewe to the lamb via milk or colostrum was not yet clear.
The use of colostrum from other dams and cross-fostering have been common practices in sheep flocks and goat herds for many years and have not been associated with epizootics of scrapie. The incidence of scrapie has reduced significantly since the introduction of the National Scrapie Plan in 2001 and in Great Britain in 2007 only 31 cases of classical scrapie were identified in animals from flocks and herds that were not already subject to control measures. Accordingly, for the majority of flocks and herds in which scrapie is not known to be present, the risk of spreading scrapie does not out- weigh the significant nutritional and immunological benefits of using stored colostrum and cross-fostering.
The findings reported by Konold and others (2008) indicate that farmers seeking to reduce the risk of introducing scrapie should not use colostrum or milk from other flocks or herds, especially those where scrapie is known to have occurred in recent years or those of unknown scrapie status. In intensively managed sheep flocks that also contain animals which may be more susceptible to classical scrapie, and within intensively managed goat herds, farmers should also consider the risk of spreading scrapie using pooled colostrum and milk. In flocks and herds that are subject to compulsory scrapie controls, the use of cow colostrum and artificial milk replacers should be considered as an alternative.
In all cases farmers are advised to discuss the best strategy for flock/herd management with their private veterinary surgeon. Keepers of sheep and goats are reminded that scrapie is a notifiable disease and that suspected cases in either sheep or goats in their care must be reported to the local Divisional Veterinary Manager.
FRANSCINI, N., GEDAILY, A. E., MATTHEY, U., FRANITZA, S., SY, M. S., BÜRKLE, A.,GROSCHUP, M., BRAUN, U. & ZAHN, R. (2006) Prion protein in milk. PLoS ONE 1, e71
KONOLD, T., MOORE, S. J., BELLWORTHY, S. J. & SIMMONS, H. A. (2008) Evidence of scrapie transmission via milk. BMC Veterinary Research 4, 14[Medline]