WASHINGTON, April 15 (UPI) -- Two U.S. cows from 1997 that recent media reports indicated might not have been properly screened for mad cow disease were both tested multiple times and were found negative for the deadly disease, United Press International learned in a two-year investigation of the cases.
At the time both cases occurred, there was initial suspicion they might be positive for mad cow disease -- also known as bovine spongiform encephalopathy or BSE -- but the UPI investigation turned up documents and witnesses that strongly indicated the cows were negative.
UPI decided not to publicize the cases due to documented evidence of the negative test results and the strong opinion of several internationally recognized BSE experts that the U.S. Department of Agriculture had handled the cases appropriately and legitimately had ruled out mad cow disease. Due to the attention the cases have received in recent media reports, however, UPI is now publishing the information it has gathered.
In the first case, in May 1997, a cow with signs of a brain disorder appeared at Oriskany Falls Packing Plant in Oriskany Falls, N.Y. At the time, USDA inspectors, including agency veterinarian Masuo Doi, became concerned the cow might have contracted BSE.
Subsequent tests detected no traces of the BSE pathogen, however, and produced no indication the cow was infected, according to USDA documents obtained by UPI via the Freedom of Information Act.
Top BSE experts reviewed the documents for UPI and all agreed the cow looked negative and even commended the USDA's handling of the case.
In addition, a portion of the cow's brain was secretly transferred to the National Institutes of Health, which independently tested the sample and again found no evidence of BSE.
Another cow that appeared at the same packing plant in August 1997 was tested using three different techniques and produced no indication it had BSE or any similar disease, according to USDA testing records UPI obtained via Freedom of Information Act requests.
Doi, who was involved in both cases, was not aware of the negative results of the NIH test on the first cow until last February, when he was informed by UPI. He then said he accepted that the animal did not have BSE.
The Canadian Broadcasting Corporation, which aired television, radio and print stories about the cases Tuesday, used clips of an interview conducted with Doi before he was informed of the negative NIH test results. The segment stated that Doi "says he is haunted by fears that the right tests were not done and that his own department did not properly investigate whether the cow had BSE."
The CBC story also referred to the Oriskany Falls plant as the slaughterhouse that "eight years ago may have become the home of the first American case of mad cow."
Felicia Nestor, a consultant to Public Citizen who was peripherally involved in the two cases and featured in the CBC story, sent a letter to CBC Producer Timothy Sawa on April 6 -- six days before the segment went to air -- clarifying that she and Doi both had concluded it was impossible to determine whether either cow had BSE.
Referring to "the possibility that either of the two cows had the disease," Nestor wrote, "At this point, we think it impossible to draw that conclusion," due to evidence to the contrary.
Nestor also expressed her concern that Sawa did not inform her during an on-camera interview about the NIH negative test on the May cow or that a test that came back positive on the August cow later was found to be contaminated and invalid.
"From the evidence I am aware of at this point, it looks like these cows were negative," Nestor told UPI. She added she is more concerned about cows that were never tested for BSE than "anything about these cases."
Sawa and CBC Executive Producer Susanne Reber did not respond to UPI requests for comment. From January through March 2005, a CBC crew including Sawa collaborated with UPI on the mad cow investigation. UPI subsequently withdrew from the collaboration.
Doi said Thursday he did not think the CBC stories accurately portrayed his position on the cases. The context of the stories "kind of twisted" my position, he said.
"I told Timothy (Sawa) you can't come up with presumptive conclusions whether (the August cow) was negative or positive, you just have to leave it as unknown," Doi added. "I don't think you have enough to say that BSE is being covered up in the United States," he said.
The USDA rejected the assertion the cows were improperly tested for BSE.
Agency spokesman Jim Rogers told UPI he had contacted the CBC and complained that their coverage of the cases omitted pertinent details from the USDA documents indicating both cows had been extensively tested and no trace of BSE was found.
"We showed them the documents ... they just chose to ignore it," Rogers said.
The May 1997 animal initially generated alarms internally at the USDA. Pathologists at the agency's laboratory in Athens, Ga., observed microscopic holes or spongiform changes in the brain tissue, which can be an indication of mad cow. However, the Athens lab did not normally conduct BSE tests and the holes were later determined to be in the wrong region of the brain for BSE. The holes were in the white matter of the brain, rather than the gray matter, where they typically occur when caused by the mad cow pathogen.
Still, the agency rushed the brain samples to its National Veterinary Services Laboratory in Ames, Iowa, which specializes in conducting BSE tests. The USDA convened a panel of experts, including some from the University of Iowa, who looked at the brain tissue and quickly concluded it was obviously not BSE. Further tests conducted at Cornell University indicated the cow had contracted a rare brain disease called progressive ataxia.
The agency also ran two types of tests, called immunohistochemistry and Western blot, that are used to detect prions, thought to be the pathogen that causes mad cow. Neither test picked up any evidence of prions.
It does appear that a region of the brain known as the obex -- which is preferred for testing for BSE because it is where prions typically concentrate -- was missing from the tissue sample, but experts said it still was possible to arrive at a solid conclusion the cow in this case did not have BSE.
In addition, missing obex is not uncommon and happens probably in every country that tests for BSE, according to Elizabeth Mumford, a veterinarian and BSE expert at Safe Food Solutions in Bern, Switzerland, a company that provides advice on reducing mad cow risk to industry and governments.
Mumford said she would be more comfortable in the final diagnosis if the obex had been tested, but added, "I still think it is likely a case of governmental panic over an apparent something that really did turn out to be nothing."
Doi sent the secret tissue sample to Joe Gibbs, the head of the NIH's Laboratory for Central Nervous System Studies, a now-defunct lab that had been conducted groundbreaking work on made cow and similar disorders in humans.
Bruce Johnson, a former NIH scientist who conducted the test on the sample, said he remembered the case.
"That was a negative cow," Johnson told UPI, noting he tested at least three different samples from the brain tissue using the Western blot method. "It was clearly negative," he said.
Johnson said he did not know whether the cow's obex was included in the samples he tested, but noted he had worked extensively with mad cow-like diseases at the NIH in humans and a variety of animal species. Based on the cow's advanced symptoms, he said, if the cow had been infected with BSE, he likely would have detected prions in other regions of the brain.
Johnson also said he knew Joe Gibbs quite well and felt certain if Gibbs had thought for a moment the cow was positive, he would have published an urgent paper about it in a scientific journal, because it would have been the first case of mad cow disease in the United States.
Several mad cow testing experts reviewed the records from the first case for UPI and all agreed the USDA acted properly.
"It seems to me that USDA went above and beyond the book in dealing with this case, and legitimately ruled out BSE," said one of the BSE experts, who requested anonymity. The expert, who works at one of the most respected BSE labs in the world, added, "They handled it very well."
Stephen Dealler, a medical microbiologist at Britain's Lancaster Royal infirmary, who has been researching BSE since it first appeared in the United Kingdom in the 1980s, told UPI, "I have had a look and what it shows to me so far is that they (the USDA) have tried quite hard and were extremely worried at the time ... but have got good reasons to say that no BSE was found."
Dealler jokingly said he was embarrassed he could not find much to criticize the agency for, because he had developed a reputation of being a bulldog on BSE.
"I am very confident that the proper diagnosis has been made," said a veterinary pathologist specializing in the diagnosis of neurological diseases and transmissible spongiform encephalopathies, or TSEs, who works at another of the premiere BSE testing labs in the world. The source also requested confidentiality.
"I think they did enough to rule out BSE in this case," the pathologist told UPI.
In the August 1997 case, another cow with neurological symptoms appeared at Oriskany Falls. This time, Doi obtained cerebrospinal fluid from the animal and sent it to Joe Gibbs. Gibbs tested the sample using a patented procedure he was developing for diagnosing a disorder similar to mad cow disease that occurs in humans. The CSF test came back positive, but the sample contained blood, which would cause the test to turn positive whether the animal was infected with mad cow or not.
It is unclear whether Gibbs, who is now deceased, understood the ramifications of blood contamination or just wanted to double-check the status of the cow, but he called Linda Detwiler, a veterinarian and head of the USDA's BSE surveillance program at the time, and asked her to look into the matter.
The cow's brain already had been screened using immunohistochemistry -- the normal screening method used for BSE suspects -- and it was negative, but to make sure nothing had been overlooked, Detwiler asked the USDA lab to run the Western blot, which also found nothing to indicate BSE.
A report in USDA's testing records notes that a histopathological examination -- a rudimentary test not considered reliable for excluding mad cow cases -- was "of questionable validity because it is unknown whether" the tissue being examined included the obex region.
The report went on to state, however, the examination "revealed no combination of lesions, which is consistent with any transmissible spongiform encephalopathy, including (BSE)."
Based on these examinations, the lab concluded, "No evidence of infection by any agent which is known to cause a transmissible spongiform encephalopathy was found."
Mumford reviewed the records of the case for UPI and said, "I think actually they did a good job."
She said her colleagues in Switzerland also had looked at the documents and they agreed there was nothing to indicate this cow might have been positive. "There's no alarm bells ringing over on this side of pond," she said.
Detwiler, who is now retired from the USDA, but is still respected by BSE experts and has a reputation for being forthright, told UPI, "I didn't have any doubt then or now that it wasn't BSE."
Steve Mitchell is UPI's Medical Correspondent. E-mail: email@example.com