Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie

Abstract

Macerates of bovine brain infected with bovine spongiform encephalopathy (BSE) agent, and rodent brain infected with the 263K or ME7 strains of scrapie agent, were subjected to porous-load autoclaving at temperatures between 134 and 138 degrees C for < or = 60 min. Bioassay in rodents showed that none of the regimens produced complete inactivation. Homogenates of BSE-infected bovine brain were exposed for < or = 120 min to solutions of sodium hypochlorite or sodium dichloroisocyanurate containing < or = 16,500 ppm available chlorine. There was no detectable survival of infectivity after the hypochlorite treatments but none of the dichloroisocyanurate solutions produced complete inactivation. Homogenates of BSE-infected bovine brain, and rodent brain infected with the 263K and ME7 strains of scrapie agent, were exposed for < or = 120 min to 1M or 2M sodium hydroxide but no procedure produced complete inactivation of all agents tested.

Quantifying BSE control by calculating the basic reproduction ratio R 0 for the infection among cattle

“…Next, q 21 represents the expected number of new maternally infected individuals from one (average) feed infected individual. One (average) feed infected animal is distributed over all possible ages at infection according to the density.…”

“…Using (18), we analyzed titration data from mouse bio-assays of Taylor [22], [21] and Schreuder et al [20] for the effect of heating and rendering on prion survival. Generalized linear modelling (GLM, see [19]) with a binomial distribution and a complementary log-log link function is applied to the data using GENSTAT v5, which estimates the constant p and its standard error.…”

“…Taylor et al ([22], [21]) tested a continuous vacuum rendering process with high fat content, which was commonly used in the UK since the 1970s. Schreuder et al…”

Effects on instruments of the World Health Organization–recommended protocols for decontamination after possible exposure to transmissible spongiform encephalopathy–contaminated tissue

“…They are not completely inactivated by conventional sterilization methods such as steam autoclaving (even at elevated temperatures) or by ethylene oxide gas. [2][3][4][5][6] Transmission of CJD in humans and animals by contaminated instruments has been demonstrated, but the devices were not subjected to modern cleaning, disinfection, and sterilization methods. [7][8][9] In the absence of any scientific study demonstrating successful decontamination, there is a growing public health concern regarding the spread of the disease by potentially contaminated surgical or dental instruments subjected to standard hospital cleaning and sterilization protocols.…”

Improved infection control in the prevention of variant Creutzfeldt‐Jakob disease in Australia: costs and benefits

“…First, the prion is difficult to remove from surgical instruments. 3,4 Second, the prion has been detected in the appendix of a patient in the pre-clinical stage of the disease. 5 Third, the prion has been demonstrated in the lymphoreticular tissues of patients with confirmed vCJD.…”