“Our enhanced BSE surveillance program has been an enormous undertaking, but well worth the effort,” said Johanns. “We can now say, based on science, that the prevalence of BSE in the United States is extraordinarily low. The testing and analysis reinforce our confidence in the health of the U.S. cattle herd, while our interlocking safeguards, including the removal of specified risk materials and the feed ban, protect animal and human health.”
The estimate of BSE prevalence in the United States is based on data gathered from not only the enhanced surveillance effort that has been underway since June 2004, but also from surveillance conducted in the United States for the five years prior, a total of 730,000 samples. USDA experts used two different methods, the BSurvE Prevalence B method and the Bayesian birth-cohort method, to analyze the prevalence of BSE based on all of the surveillance data.
The findings of the two methods were similar, indicating that the most likely number of cases present in the United States is between four and seven animals. Therefore, USDA concludes that the prevalence of the disease in the United States is less than one case per million adult cattle, based on an adult cattle population in the country of 42 million animals.
The surveillance program is not part of U.S. food safety protections. The system of interlocking safeguards protects animal and public health. The most important safeguards are the removal of specified risk materials from the food supply, along with the Food and Drug Administration’s (FDA’s) 1997 ruminant-to-ruminant feed ban. Science indicates that the longer the FDA’s feed ban is in place, the lower the prevalence of BSE will be in the United States.
USDA will use the prevalence analysis, once it is peer-reviewed, and international standards set by the World Organization for Animal Health (OIE) to design an ongoing BSE surveillance program for the United States. USDA said the data and analysis would also assist in making science-based policy and regulatory decisions related to the disease.
USDA’s enhanced BSE surveillance program followed the detection of the disease in an imported animal in December 2003. The target population of cattle tested included those animals where the disease is most likely to be found if it is present: non-ambulatory cattle, cattle exhibiting signs of central nervous disorders, or any other signs that may be associated with BSE, including emaciation or injury and dead cattle. Samples were drawn from more than 5,000 locations across the United States, including slaughter plants, renderers, farms, public health laboratories, veterinary diagnostic laboratories, and salvage slaughter facilities.
The agency is providing its analysis to outside experts for a scientific peer review and making it available to the public.
In a separate announcement, USDA’s Animal and Plant Health Inspection Service and FDA completed their investigations regarding a cow that tested positive for BSE in Alabama in March (see “Newsline” in the April 2006 Render). Born prior to FDA’s 1997 feed ban, the 10-year-old red crossbreed non-ambulatory cow was euthanized and buried on the farm.
APHIS and Alabama state officials investigated 36 farms and five auction houses and conducted DNA testing on herds that may have included relatives of the index animal. Investigators were unable to find any related animals except for two recent calves of the affected animal. The most recent calf was located at the same farm as the index animal and the second calf died the year before. The living calf is currently being held at APHIS’ National Veterinary Services Laboratory in Ames, IA, for observation. The investigation did not reveal the BSE-positive animal’s herd of origin, which was not unexpected due to the age of the animal and lack of identifying brands, tattoos, and tags.
FDA conducted a feed investigation into local feed mills that may have supplied feed to the index animal after the 1997 feed ban and found that all local feed mills that handle prohibited materials have been and continue to be in compliance with the FDA feed ban.
Canada Confirms Fifth Case
On April 16, 2006, the National Centre for Foreign Animal Disease in Winnipeg, Canada, confirmed BSE in a cow from British Columbia. No part of the animal entered the human food or animal feed systems.
The Canadian Food Inspection Agency (CFIA) was able to identify the animal’s exact date of birth and birth farm – two critical elements required to trace other animals of interest, as defined by the World Organization for Animal health, or OIE. The animal, a six-year-old dairy cow, developed the disease after the implementation of Canada’s feed ban, which CFIA said is common to almost all BSE-affected countries that have introduced feed controls.
By mid-May, 23 live cattle potentially exposed to the same feed as the affected animal were identified, with 12 testing negative for BSE. The remaining 11 animals were being evaluated for compensation purposes and will be tested. These animals were part of 146 cattle investigated from the affected animal’s feed cohort and its two most recently born offspring. Besides the 23 cattle, investigators concluded that 74 cattle had previously died, 34 cattle were deemed untraceable due to lack of information, and 15 cattle were exported to the United States. CFIA stated that 34 untraceable animals out of 146 is not an unusual rate for investigations of this type and that finding additional cases of BSE in a feed cohort is unlikely. Canadian and American authorities collaborated fully to trace the animals.
Of the 15 cattle exported to the United States, one of the animals had been located, euthanized, and tested, while the disposition of the remaining 14 animals was still being determined at press time. USDA officials reiterated CFIA’s statement about the possibility of finding additional cases of BSE in a feed cohort.
“Experience worldwide has shown us that it is highly unusual to find BSE in more than one animal in a herd or in an affected animal’s offspring,” stated USDA Chief Veterinary Officer John Clifford. “However, we will continue to work with Canada to locate as many animals of interest in this case as possible. It is important to remember that the United States maintains a series of interlocking safeguards which are what protect animal and public health.” These safeguards include the removal of specified risk materials from the food supply and FDA’s 1997 ruminant-to-ruminant feed ban, with recent figures showing compliance rates at near 100 percent (see page 34).
CFIA’s feed investigation is being reviewed and will be posted to their Web site in a final report.
Newsline - June 2006 Render