Neurologist Claims Farmed Fish Might Pose Risk for Mad Cow Disease

A University of Louisville neurologist has published a report questioning the safety of farmed fish that are fed cattle byproducts, which could allegedly present a risk of transmitting mad cow disease to humans. Robert P. Friedland, et al, “Bovine Spongiform Encephalopathy and Aquaculture,” Journal of Alzheimer’s Disease (June 2009). Friedland and his co-authors have urged government regulators to ban feeding cow meat or bone meal to fish until the safety of this common practice can be confirmed.

“We have not proven that it’s possible for fish to transmit the disease to humans,” Friedland was quoted as saying. “Still, we believe that out of reasonable caution for public health, the practice of feeding rendered cows to fish should be prohibited. Fish do very well in the seas without eating cows.” Although no cases of mad cow disease have been linked to eating farmed fish, the report claims that this does not assure that feeding rendered cow parts to fish is safe. The incubation period of mad cow disease, Friedland says, “may last for decades, which makes the association between feeding practices and infection difficult.”

While the risk of transmitting mad cow disease to humans who eat farmed fish appears to be low, Friedland alleges it is possible for a disease to be spread by eating a carrier that is not infected itself. He asserts that eating diseased cow parts could cause fish to experience a pathological change that allows the infection to be passed between two species.

Creutzfeldt-Jakob disease, the human form of transmissible spongiform encephalopathy, is an untreatable fatal disease that can be contracted by eating parts of an infected animal. Most countries have outlawed feeding rendered cow material to other cattle because the disease is so easily spread within the same species. In the United Kingdom, 163 people have reportedly died from eating infected beef. See Science Daily, June 17, 2009.