Brewer discusses BSE during Food Safety Symposium
STILLWATER, Okla. – Susan Brewer, professor at the University of Illinois, was one of six speakers during the recent Food Safety Symposium hosted by the Food & Agricultural Products Center.
Brewer discussed bovine spongiform encephalopathy, commonly known as BSE, and the problem and concerns for the meat industry.
Brewer said BSE is a progressive, degenerative disease of the central nervous system. Infection occurs in calves at approximately two years of age. Symptoms onset at approximately five years and could result in death or humane destruction in four months.
"BSE is a transmissible spongiform encephalopathy, or TSE, that is neither bacterial or viral," she said.
Some related TSEs include scrapie in sheep and goats, transmissible feline encephalopathy, chronic wasting disease in mule deer and elk, human diseases such as Creutzfeldt-Jakob disease, or CJD, and new variant CJD.
In regards to whether BSE causes foodborne illness, Brewer said there are some questions that need to be answered. Those questions include: did cattle contract BSE from diseased sheep through feed, can man contract BSE from beef, and is that the source of new variant CJD?
Brewer compared the rendering practices of the United States to the United Kingdom and explained the different tissues responsible for transmission. Transmission takes place from dam to fetus in sheep. Oral intake of certain tissues, such as the brain, spinal cord and retina, in cattle and sheep can transmit the diseases.
Brewer then went on to discuss prions. Normal prions or proteins exist in the nerve cell membrane. The proteins can then convert into the infective isoform or scrapie.
"Different strains produce different effects in animals, such as different areas of the brain affected, different appearance of damage in affected areas and different symptoms," Brewer said. "Strain typing is based on brain lesion pattern, glycoform profile and the kind of amyloid plaque formed."
Brewer used CJD as an example of a disease found in humans. The onset age is over 65; however, the incubation period is about 25 years. The course of the disease is fast, and death could occur in less than six months. Some of the symptoms are muscle spasms, progressive dementia and movement coordination problems.
"One hundred forty-five people have died of CJD to date," Brewer said.
In addition, Brewer said new variant CJD looks similar to BSE. The onset age is approximately 42 years with an incubation period of four to five years and death in one to two years. The symptoms include psychiatric, memory loss and coordination problems.
"No cases of new variant CJD have occurred in the United States," Brewer said.
However, new variant CJD occurred in the United Kingdom soon after BSE was identified, Brewer said. There was concern that BSE and new variant CJD were related. The hypothesis was that new variant CJD occurred due to consumption of high-titre BSE-infected beef products.
Brewer concluded her presentation by saying BSE is an industry and a food safety challenge.
Stanley Gilliland, FAPC food microbiologist and chair of the symposium, said the FAPC was lucky to have Brewer participate as a speaker during the Food Safety Symposium.
“Dr. Brewer has participated in extensive research about BSE and is highly knowledgeable about the subject,” Gilliland said. "Her presentation was extremely beneficial to the participants of the symposium."
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