Transmissible degenerative encephalopathy agents are relatively resistant to standard decontamination procedures. Bovine spongiform encephalopathy (BSE) agent was inactivated by sodium hypochlorite but not sodium dichloroisocyanurate; 1M or 2M sodium hydroxide was unreliable for BSE and scrapie agents. BSE infectivity survived a two‐year exposure to formol saline. Porous‐load autoclaving at 134‐138°C was ineffective with BSE and scrapie agents, and resistance to porous‐load autoclaving was enhanced by prior exposure to ethanol. Gravity displacement autoclaving at 132°C was also ineffective with BSE agent. Gravity displacement autoclaving at 121°C was effective with scrapie agent if it was exposed to 2M sodium hydroxide during autoclaving. After BSE‐spiked material was processed through facsimiles of EC rendering processes, infectivity was recoverable in the meat and bonemeal produced by four of these processes. Using scrapie‐spiked material, infectivity was recoverable in all meat and bonemeal samples except those derived from processes which used steam under pressure.
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