NIAA hosts BSE experts, addressing the science of the debate
BOWLING GREEN, Ky. (May 16, 2005) — The debate on bovine spongiform encephalopathy (BSE) is seemingly endless, particularly with the number of parties involved in litigation and political positioning regarding BSE and international trade. Still, the science of BSE is the key factor in the decision-making process for industry leaders.
At its annual meeting in April, the National Institute for Animal Agriculture (NIAA) brought together two BSE experts, Will Hueston of the Center for Animal Health and Food Safety at the University of Minnesota, and Brian Evans, chief veterinary officer of Canada with the Canadian Food Inspection Agency (CFIA). The evening session, sponsored by the Canadian Consulate General in Minneapolis, Minn., gave attendees a candid discussion regarding the science of BSE.
“Although BSE has its origins over two decades ago, there has been significant advancement in our collective understanding of the measures necessary to effectively protect animal and public health, which has been the foundation of our decision making,” Evans said.
The implementation of these measures has resulted in a substantive decrease in BSE at the global level. At the height of the outbreak in the United Kingdom, there were more than 102 cases per day. In 2004 there were less than 900 cases reported worldwide, and, as of the end of April, the numbers for 2005 are less than 150. Of the approximately 189,000 cases reported since 1986, 5,219 have been outside of the United Kingdom, with a total of four in North America.
Evans added that every country’s experience with BSE is different based on the route and magnitude of exposure, the scope and duration of the mitigating measures in place and the level of compliance achieved. Canada and the United States have worked cooperatively in instituting a suite of measures, including comparable feed bans introduced in 1997, to prevent the amplification and spread of the disease.
Hueston spoke on the epidemiology of BSE, and the importance of the feed bans in minimizing risks. “Available evidence indicates that the incubation period of BSE is inversely proportional to exposure,” he said. “This implies that with no feed controls, the level of BSE circulating in the feed increases and more cases are found more often and the cases are younger. With the feed ban, as in North America, the BSE agent in feed decreases, as do cases, and the age of diagnosed cattle is higher. (See Fig. 1 below.) Studies tell us that the larger the exposure, the shorter the incubation, while the smaller the exposure, the longer the incubation.”
Hueston also discussed research on the distribution of the BSE agent in cattle tissues, noting that the distal ileum, brain and spinal cord contain the highest levels of the agent. Additionally, research has shown that no evidence exists to date that the BSE agent is found in cattle muscle.
Evans indicated that the North American BSE situation is unique, as consumer confidence has been maintained in the beef industry. He added that this is unprecedented relative to other countries, and has resulted in a different environment for policy establishment. The North American experience allows a focus on progressive, science-based, integrated measures.
Though a number of trade barriers still exist for both the U.S. and Canada, Evans said that progress is being made in market recovery as more countries move to adopt import policies that reflect the science-based standards for safe trade developed by the World Organization for Animal Health (OIE). Hueston added that the BSE risk has become partially fear-driven, as opposed to evaluating the true danger that is considered among the scientific community.
The trade issues have seen some progress recently, particularly with the Japanese moving forward with revised testing requirements; however, the future remains to be seen.
Presentations can be viewed at www.animalagriculture.org; simply click on the proceedings link and go to the 2005 Annual Meeting page.
The NIAA provides a forum for building consensus and advancing solutions for animal agriculture and provides continuing education and communication linkages to animal agriculture professionals. For more information about NIAA, visit www.animalagriculture.org or call (270) 782-9798.
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— This article was provided by NIAA.
