Weekly Topic: BSE lessons-learned shape the handling of chronic wasting disease
James Kincheloe

Mistakes in BSE response lead to changed attitudes

In 1990, in the midst of the United Kingdom's Bovine spongiform encephalopathy (BSE) outbreak and growing concern that the disease could cause Creutzfeldt-Jakob Disease in humans, UK agriculture secretary John Gummer attempted to feed his 4-year old daughter a burger in front of camera crews to demonstrate the safety of British beef.

Chief Medical Officer Sir Donald Acheson claimed he had no hesitation in saying “beef can be eaten safely by everyone, both adults and children, including patients in hospitals.”

In 1995, 19-year-old Stephen Churchill died of a neurologic disease identified as a variant of Creutzfeldt-Jakob Disease (vCJD) and linked to consumption of BSE infected meat the following year. Both diseases are prion diseases, a unique class of disease thought to be spread by proteins as opposed to viruses or bacteria. Over two hundred people worldwide, the majority of them British, would die of the long incubating disease.

Investigations and inquiries into the government’s handling of the outbreak forever changed the way policy makers view public health risk, forcing officials and health professionals to put more weight on alarming scientific advice that considered worst case scenarios. Furthermore, officials were urged to be more open with the public on health issues and acknowledge risks.

The Guardian
BBC

Mixed evidence of Chronic Wasting Disease’s risk to humans not to be taken lightly

Chronic Wasting Disease (CWD), a prion disease affecting cervids, was first found in the 1960’s and has since spread to over 20 US states (including Minnesota) in farmed and wild populations, regions of Canada, South Korea, and recently was found in Europe. No cases of human disease have been linked to consuming or handling infected animal products.

Prion diseases, however, have a notoriously long incubation periods, sometimes taking decades to develop into clinical disease. For example, patients who received contaminated hormone donor samples over forty years ago are still developing CJD from the exposure.    

When taking the long incubation periods into account and the history of BSE and CJD, scientists are serious about researching the potential for CWD to affect humans. A few recent examples of research: A study showed the ability of the CWD to be passed to squirrel monkeys through multiple routes including oral transmission. One study showed Macaques, more closely related to humans, did not develop the disease after exposure when observed in some cases for over 10 years, while another more recent study showed infection to the monkeys after oral exposure.

In addition, in laboratory studies, straight CWD prions were able to convert human normal proteins to prions. The evidence is far from clear and from prior experience, scientists recommend caution.    

Centers for Disease Control and Prevention
PubMed

Authorities take action against Chronic Wasting Disease

Considering the potential for CWD to affect humans as well as its impacts on cervid populations, governments take the threat of the disease seriously.

In the United States, CWD is a reportable disease. At the federal level, the U.S. Department of Agriculture has a herd certification program to help keep farmed herds CWD free, helps assist states with controls and tracing the disease, and offers compensation to farmers who lose their herds due to CWD.    

Locally, the Minnesota Board of Animal Health requires all cervid farms to register with the state, and tracks animal movements as well as tests all dead or slaughtered animals for CWD. The Department of Natural Resources tracks and attempts to stop the spread of the disease in wild populations. These programs, both federally and at the state level, are actively being adjusted as new evidence and need for control comes to light.

Hunters and consumers of venison are being openly warned. The Department of Natural Resources has a section on their website regarding the safety of the deer for consumption. “Currently, there is no evidence that CWD poses a risk for humans; however, public health officials at the Center for Disease Control (CDC) recommend that hunters do not consume meat from animals known to be infected.” Included is a link to the CDC website.

Other states have been even more proactive in their warnings, with Wisconsin releasing handouts for hunters specifying how to minimize their risk of exposure to the disease while hunting the animal through processing and consumption. Regulatory bodies do not want to be accused of failing to warn the public about risk from a prion disease again.  

USDA
Minnesota Department of Natural Resources
Wisconsin Department of Natural Resources

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James Kincheloe

James Kincheloe

James received his DVM from the University of California, Davis. He has worked as a herd veterinarian for dairy cows and a small animal veterinarian in California. Jim is interested in agricultural and infectious disease policy, and has collaborated on domestic and international projects across the public health spectrum.