Virologic and Neurohistologic Findings in Dairy Goats Affected with Natural Scrapie

Abstract

Virologic and neurohistologic findings in three dairy goats that became affected with scrapie while living with naturally infected Suffolk sheep were essentially like those in affected sheep. Virus, detected by mouse inoculation, was widespread in non-neural sites, particularly in lymphatic tissues and intestine. In most sites, titers of virus ranged from 3.0 to 3.5 log₁₀ mouse intracerebral LD₅₀/30 mg of tissue. Virus was in nervous tissue in much higher titer. Ranging from 5.1 to 5.8 log₁₀, the highest mean titers were in the diencephalon, midbrain, medulla oblongata and cerebellar cortex—sites of the most severe histologic changes. Although these changes were like those in naturally affected Suffolk sheep, they differed somewhat from those in goats affected with the experimental disease. Spongiform alteration of neuropil was minimal, and the more rostral parts of the brain, such as corpus striatum, globus pallidus and septal area, had few changes. Concentrations and distribution of virus in non-neural tissues were consistent with the conclusion that scrapie virus no doubt can be maintained by contagion in a herd of goats living apart from infected sheep.