Methods for detection of the presence or absence of PrP.sup.Sc in a biological sample suspected of having them comprising the steps of concentrating the PrP.sup.Sc as may be present in the sample by substantially separating the PrP.sup.Sc from the sample matrix; labeling the concentrated PrP.sup.Sc with at least one molecular label to produce labeled PrP.sup.Sc; and detecting the labeled PrP.sup.Sc on an instrument capable of detecting an attomole quantity of labeled PrP.sup.Sc, and wherein the duration of time between concentrating the PrP.sup.Sc and analyzing the labeled PrP.sup.Sc is about 48 hours or less.
STATEMENT OF FEDERAL RIGHTS
 These inventions were made with government support under Contract No. DE-AC52-06 NA 25396, awarded by the U.S. Department of Energy. The government has certain rights in the inventions. These inventions further were made with support from grant number DAMD17-03-1-0368, awarded by the Army Medical Research and Materiel Command, and grant number HL063837, awarded by the National Heart Lung Blood Institute.