Friedland and co-authors suggest, despite any evidence or anything outside their own speculation, that farmed fish byproducts rendered from cows, like bone meal, could transmit Creutzfeldt Jakob disease, commonly known as mad cow disease, to humans. Despite the lack of evidence, they are urging government regulators to ban feeding cow meat or bone meal to fish until the safety of this common practice can be confirmed. How can you further prove something is safe that has been in use for decades without issue?
Creutzfeldt Jakob disease is an untreatable, universally-fatal disease that can be contracted by eating parts of an animal infected with bovine spongiform encephalopathy. An outbreak in England attributed to infected beef prompted most countries to outlaw feeding rendered cow material to other cattle because the disease is so easily spread within the same species. There have been 163 deaths from Creutzfeldt Jakob disease in the United Kingdom attributed to eating infected beef. Bovine spongiform encephalopathy has been identified in nine Canadian and three U.S. cattle.
Obviously after a lot of people get sick is too late but the risk of transmission of bovine spongiform encephalopathy (BSE, mad cow disease) to humans who eat farmed fish is low (in the scientific sense - in the colloquial sense the word would be 'impossible') because of barriers between species. Despite this, the authors say it is possible for the disease to be spread by eating a carrier that is not even infected itself. They claim it's also possible that eating diseased cow parts could cause fish to experience a pathological change that allows the infection to be passed between the two species.
"We have not proven that it's possible for fish to transmit the disease to humans. Still, we believe that out of reasonable caution for public health, the practice of feeding rendered cows to fish should be prohibited," Friedland said. "Fish do very well in the seas without eating cows," he added.
"The fact that no cases of Creutzfeldt Jakob disease have been linked to eating farmed fish does not assure that feeding rendered cow parts to fish is safe. The incubation period of these diseases may last for decades, which makes the association between feeding practices and infection difficult. Enhanced safeguards need to be put in place to protect the public," Friedland said.