A new study in the American Journal of Pathology has shown that bovine spongiform encephalopathy (BSE), commonly known as “mad cow” disease”, spreads in the autonomic nervous system (ANS) to the central nervous system (CNS) before it can be detected. Mad cow is a fatal disease in cattle that can be transmitted to humans who eat infected tissue. There isn’t much that scientists know about the spread of the BSE prion in its early incubation period. Other studies have reported that the autonomic nervous system was affected only after the central nervous system is infected.
The autonomic nervous system controls involuntary actions, such as heart rate, blood pressure, and the functions of major organs. It consists of the sympathetic ANS, the parasymphathetic ANS, and the enteric nervous system. The central nervous system is the part that controls your brain and makes up your consciousness; it consists of the brain and spinal cord. It usually takes five years from infection before the disease can be detected. But in the study, 56 calves were infected orally with BSE; samples were collected every four months for the next three and a half years. Scientists found the pathological prion (a misfolded protein that is not alive) in the gut and in the ANS but not in the CNS.
Infection was found in the spinal cord of one animal only 16 months after infection. Dr. Martin H. Groschup, one of the study’s authors, said, “the clear involvement of the sympathetic nervous system illustrates that it plays an important role in the pathogenesis of BSE in cattle. Nevertheless, our results also support earlier research that postulated an early parasympathetic route for BSE.”
The study’s authors believe that there are three routes for the BSE prion to get to the brain: sympathetic, parasympathetic, and spinal cord, in order of importance. Knowing how the prion gets to the brain does have food safety implications.