On June 24, 2005 the U.S. Department of Agriculture (USDA) confirmed the second case of mad cow disease (Bovine Spongiform Encephalopathy or BSE) in the United States. The previous case was in December 2003, in a cow imported from Canada. This new occurrence is unprecedented in that it is the first apparent case of BSE in a U.S.-born cow. People who eat BSE-contaminated meat are potentially at risk of developing the human form of the disease known as variant Creutzfeldt-Jakob disease or vCJD. However, since the meat of this cow did not enter the food supply, there was no risk of a person contracting vCJD.
Mad cow in animals and vCJD in humans, are prion-related diseases, which result in very serious neurological symptoms with no available treatment. Theoretically, if a person was to become infected with vCJD there exists the possibility of them donating blood and bringing the disease into the blood supply.
The USDA disclosed more information on the infected animal. It was a 12 year old Brahman cross-breeding cow from a ranch in Southeast Texas. It was initially labeled a "downer" because it could not walk on its own and, per standard practice was deemed unfit for human consumption. Months of delays caused by conflicting test results then ensued. Discrepancies were not reconciled until intervention by the USDA's Inspector General's office prompted further action. Testing done by England's Weybridge Laboratory finally confirmed the case.
According to the USDA's Chief Veterinarian John Clifford the strain of the disease in this cow was similar to one found in France. It is possible that this infection originated from BSE-contaminated feed imported from that country. Officials also revealed that in all likelihood, this particular animal, born four years prior to the 1997 ban on cow parts in cattle feed, was infected through contaminated feed.
In response, the USDA has analyzed the chain of events that led to this infection and has taken steps to improve BSE-testing protocol. Officials are also screening the Texas cow's herd of origin and tracing the feed supply in question.
The National Veterinary Services Laboratory in Ames, IA is conducting rapid-screening tests on the 67 cows that make up the original herd. USDA spokesperson Jim Rogers announced that officials have already tested 29 cows, all of which tested negative for BSE. The remaining 38 cattle are currently being screened for the disease. As per the new protocol, if results from rapid tests are inconclusive, thereby indicating the potential presence of mad cow disease, then the animal in question will be incinerated. Brain samples, taken after the cows are killed for initial rapid-screening, are then tested using the immunohistochemistry (IHC) and Western blot tests. These advanced tests are designed to detect the abnormal prion proteins responsible for mad cow disease in animals. The USDA will apply this standard of screening and follow-up testing in the hopes of preventing BSE transmission to humans.
The National Hemophilia Foundation will continue to monitor this situation and will report any significant developments.
Sources: Associated Press, June 24, 2005, Aberdeen American News, June 25, 2005, Houston Chronicle, July 1, 2005, America's Blood Centers (ABC) Newsletter, July 1, 2005, The Houston Chronicle, July 10, 2005
To read USDA Chief Veterinarian John Clifford's statement, "Regarding the Epidemiological Investigation into the Recently Confirmed BSE Case," go to www.aphis.usda.gov/lpa/issues/bse/bse_statement6-29-05.doc.
More general information about mad cow disease can be found on the USDA Web site at www.fsis.usda.gov/Fact_Sheets/Bovine_Spongiform_