Inactivation of prions in daily medical practice

The danger of transmission of non conventional agents such as prions consti tutes a risk that is difficult to evaluate as the actual understanding of t he infections mechanism is minimal. The efficacy of each procedure is evalu ated via submitting infectious particles mixed with cellular products to in activating treatments, and then by inoculating animals with fractions of th e preparation. With these protocols, some ineffective treatments can be ide ntified (for example, soaking in aldehyde), and three reference treatments are recommended by the WHO: soaking in 1 N sodium hydroxide (1 h, 20 degree s C), soaking in 12.5% bleach (1 h, 20 degrees C) and steam sterilization i n autoclave (134 degrees C-138 degrees C, 18 min). Universal precautions of asepsis and hygiene must be applied, especially in anatomo-pathological la boratories and for the re-use of medical devices in neurosurgery or in opht halmology. (C) 1999 Elsevier, Paris.