Scrapie is a neurodegenerative disease, caused by a prion, that affects sheep and occasionally goats. The last case of scrapie in North Dakota was identified in 2007.
In sheep, the animal's genotype strongly influences the incidence of disease. Genetically susceptible sheep do not become ill for several years; however, scrapie is progressive and fatal once the symptoms develop.
Transmission of scrapie is best understood in sheep. Infected animals carry the scrapie prion for life, and can transmit the agent even if they remain asymptomatic. Most animals become infected from their dam, either at or soon after birth. In genetically susceptible, infected ewes, prions may be found in the reproductive tract, including the placenta, during pregnancy. These ewes can produce either prion-positive or prion-negative placentas, depending on the genotype of the fetus Neonatal animals become infected when they lick or ingest fetal membranes and fluids. In confined lambing areas, the disease can also spread to the offspring of uninfected.
Scrapie can be found worldwide. This disease has been reported in Europe, the Middle East, Japan, Canada, the United States, Kenya, South Africa, Colombia and parts of Asia. The scrapie status of many countries is not known because they have no surveillance for this disease. Scrapie is a reportable disease in the United States.
There is no evidence that scrapie can be transmitted to humans.