According to the results of the study, undertaken by researchers at the Vet Labs Agency, Weybridge, lambs can pick up cellular prion protein (PrP) – the pre-cursor to scrapie infection – from their scrapie affected mothers’ milk.
Eighteen lambs with the most susceptible scrapie genotype, VRQ/VRQ, were fed milk from 12 scrapie affected ewes of the same genotype and 15 VRQ/VRQ sheep reared on scrapie-free dams served as controls.
Three of the lambs fed milk from scrapie-affected ewes were culled due to disease at 43, 44 and 105 days old resectively and PrP was detected in the distal ileum (short gut) of two of the lambs.
Meanwhile, a control lamb, housed in a separate pen and culled at 38 days old was also negative for PRP in a range of tissues.
Subsequently recto-anal mucosa associated lymphoid tissue was collected from the remaining 15 live lambs at seven months old and all these were positive for PrP, while similar samples taken from lambs fed milk from scrapie-free dams were all free of PrP.
Early signs of lateral transmission were also detected in two of five control group lambs mixed with the trial lambs. However, no PrP was found in the control lambs kept entirely separate from the trial lambs, but housed in the same building.
However, it is not clear if any of the animals showing presence of PrP from milk transmission would go on to develop clinical disease.