Prions survive conventional sewage treatment

Science Daily: Scientists in Wisconsin are reporting that typical wastewater treatment processes do not degrade prions. Prions, rogue proteins that cause incurable brain infections such as Mad Cow disease and its human equivalent, variant Creutzfeldt-Jakob Disease, are difficult to inactivate, resisting extreme heat, chemical disinfectants, and irradiation. Until now, scientists did not know whether prions entering sewers and septic tanks from slaughterhouses, meatpacking facilities, or private game dressing, could survive and pass through conventional sewage treatment plants.

Joel Pedersen and colleagues used laboratory experiments with simulated wastewater treatment to show that prions can be recovered from wastewater sludge after 20 days, remaining in the "biosolids," a byproduct of sewage treatment sometimes used to fertilize farm fields.

Although emphasizing that prions have never been reported in wastewater treatment plant water or biosolids, the researchers note that existing tests are not sufficiently sensitive to detect the extremely low levels of prions possible in those materials….

Magnified 158 times and stained, this light photomicrograph of brain tissue reveals typical amyloid plaques found in variant Creutzfeldt-Jakob disease (vCJD). From the Centers for Disease Control, Wikimedia Commons