Mad Elk and Mad Fish

Via ProMED-mail: last month, the New York Times reported on the spread of CWD among elk via fecal-oral transmission, due to preclinical shedding of prions.

Dr. Aiken said prions tended to bind to clay in soil and to persist indefinitely. When deer graze on infected dirt, prions that are tightly bound to clay will persist for long periods in their intestinal regions. So there is no chance chronic wasting disease will be eradicated, he said. Outside the laboratory, nothing can inactivate prions bound to soil. They are also impervious to radiation.

Also, Practical Fish Keeping reported last month on a study of mad cow and scrapie transmissibility to fish:

The authors found that while the bream never displayed clinical signs of spongiform encephelopathies during the study period, the brains of TSE-fed fish sampled two years after challenge showed signs of neurodegeneration and accumulation of deposits that reacted positively with antibodies raised against sea bream PrP. The control groups, fed with brains from uninfected animals, showed no such signs.