The development of a transmissible spongiform encephalopathy upon upta
ke of the infectious agent in feed was studied in the model system scr
apie in hamsters. Compared to single dosing, repeated dosing caused di
sease at a considerable higher incidence. The risk of infection was hi
gher when the time interval between repetitive dosing was short. There
was a statistically significant trend of clearance of infectivity wit
h time.