.Humanitarian Resource Institute:  A U.S. & International Resource on the Scope of Humanitarian Assistance

Updated: 05 August 2004

Contact: Stephen M. Apatow
Founder, Director of Research & Development
Humanitarian Resource Institute
Humanitarian University Consortium Graduate Studies
Center for Medicine, Veterinary Medicine & Law
Phone: 203-668-0282
Email: s.m.apatow@humanitarian.net
Internet: www.humanitarian.net

Transmissible Spongiform Encephalopathies in North America

 Information Sites

In The News Related Information US Geographical BSE Risk Analysis

European Commission: Scientific Steering Committee

Conclusion of the Resulting Risks: During the period covered by the European Commission Assessment of the Geographic BSE Risk of the USA (1980-1999) the US -system was not able to prevent propagation of BSE should it have entered, even if this ability was significantly improved with the MBM-ban of 1997.

Report on the Assessment of the Geographical BSE - Risk of the U.S.A. (July 2000)(220kb)

Harvard BSE Risk Assessment

Analysis finds that the U.S. is highly resistant to any introduction of BSE or a similar disease. BSE is extremely unlikely to become established in the U.S.


CJD: Increases more than 50 fold since 1979, going from 857 deaths to more than 50,000 in 2000

"Mad Cow: Linked to thousands of CJD cases?," 29, December 2003 

-- The U.S. government's monitoring system for cases of Creutzfeldt-Jakob disease, a fatal human brain illness, could be missing tens of thousands of victims, scientists and consumer advocates have told United Press International.
-- Clusters of CJD have been reported in various areas of the United States -- Pennsylvania in 1993, Florida in 1994, Oregon in 1996, New York in 1999-2000 and Texas in 1996.
-- People who develop CJD from eating mad-cow-contaminated beef have been thought to develop a specific form of the disorder called variant CJD. But new research, released last December, indicates the mad cow pathogen can cause both sporadic CJD and the variant form.
-- "Now people are beginning to realize that because something looks like sporadic CJD they can't necessarily conclude that it's not linked to (mad cow disease)," said Laura Manuelidis, section chief of surgery in the neuropathology department at Yale University, who conducted a 1989 study that found 13 percent of Alzheimer's patients actually had CJD.
-- Several studies, including the one by Manuelidis, have found autopsies reveal 3-percent-to-13-percent of patients diagnosed with Alzheimer's or dementia actually suffered from CJD. Those numbers might sound low, but there are 4-million Alzheimer's cases and hundreds of thousands of dementia cases in the United States. A small percentage of those cases could add up to 120,000 or more CJD victims going undetected and not included in official statistics.
-- At the same time autopsies have been declining, the number of deaths attributed to Alzheimer's has increased more than 50-fold since 1979, going from 857 deaths then to nearly 50,000 in 2000. Though it is unlikely the dramatic increase in Alzheimer's is due entirely to misdiagnosed CJD cases, it "could explain some of the increase we've seen," Manuelidis said.

Young Onset Dementia

Young Onset Dementia: Epidemiology, clinical symptoms, family burden, support and outcome, Dr Richard J Harvey MD MRCPsych (http://web.kamogawa.ne.jp/~miyake/yod.pdf):

Dementia affecting the under 65 years age group is increasingly recognised as an important medical and social problem. This report is based upon research carried out over a 2½ year period in two London boroughs. A comprehensive methodology was used to attempt to identify every case of dementia which began before the affected person was age 65 years and to establish a specific cause. The study identified 185 cases of young onset dementia, giving a prevalence of 67.2 cases per 100,000
at risk in the 30-64 years age group. Extrapolating these figures suggests that there may be 16,737 (95% CI: 13,975-19,879) people affected in the wider UK population. The prevalence rates for specific dementias included Alzheimer’s disease (21.7/100,000 (15.6-29.3), Vascular Dementia (10.9/100,000 (6.7-16.5)) and Frontotemporal dementia (9.3/100,000 (5.5-14.7). It was notable that Alzheimer’s disease accounted for less than half of the cases of dementia.

Presenile dementia syndromes: an update on taxonomy and diagnosis, M D Greicius, M D Geschwind and B L Miller, Journal of Neurology Neurosurgery and Psychiatry 2002;72:691-700 (http://jnnp.bmjjournals.com/cgi/content/full/72/6/691):

The four major degenerative dementias that often begin in presenescence: are reviewed. These are Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, and Creutzfeldt–Jakob disease. Their epidemiological, genetic, and clinical features are reviewed, and controversies in taxonomy arising from recent discoveries described. Particular attention is given to the pathological role of protein aggregation, which appears to be a factor in each disease. 

Related Publications

Transmissible Spongiform Encephalopathies

The article "Brain trust: Local scientist, world-renowned expert reflects on half century of work with TSEs" outlines important research associated with Transmissible Mink Encephalopathy (TME) in the U.S. in 1963, Chronic Wasting Disease (CWD) in 1979.  CWD, proved to be transmissible experimentally to mule deer, mink, domestic ferrets, squirrel monkeys and goats, is a significant finding since environmental contamination is attributed to the spread of the contagion.

According to "Transmissible Mink Encephalopathy Veterinary Services February 2002" (http://www.priondata.org/data/A_tme.html):

-- The first documented TME outbreak in the United States occurred in 1947 on one ranch in Wisconsin and then on a ranch in Minnesota that had received mink from the Wisconsin ranch.
-- In 1961, TME outbreaks occurred on five ranches in Wisconsin.
-- In 1963, outbreaks occurred in Idaho, Minnesota, and Wisconsin. Epidemiologic data from the Minnesota and Wisconsin outbreaks trace the cases in those States to one common purchased food source.
-- The most recent TME outbreak occurred on one mink ranch in Stetsonville, WI, in 1985. In the herd of 7,300 adult mink, 60 percent of the animals died.


J Comp Pathol. 1995 Oct;113(3):241-51.

Experimental infection of cattle with the agents of transmissible mink encephalopathy and scrapie.
Robinson MM, Hadlow WJ, Knowles DP, Huff TP, Lacy PA, Marsh RF, Gorham JR.

USDA-ARS Animal Disease Research Unit, Washington State University, Pullman 99164-7030, USA.

Cattle are susceptible to experimental infection with the Stetsonville isolate of the transmissible mink encephalopathy (TME) agent. To determine if they are susceptible to other TME isolates, two groups of calves were inoculated intracerebrally with homogenate of mink brain containing the Hayward isolate or the Blackfoot isolate. For comparison, a third group was inoculated with a brain homogenate from a steer infected with the Stetsonville isolate in its primary cattle passage and a fourth group was inoculated with a pool of brain homogenate from three cattle experimentally infected with a sheep and goat scrapie agent in its primary cattle passage. Clinical signs of neurological disease appeared in each steer of every group between 15 and 25 months after inoculation. An encephalopathy characterized by severe spongiform change and pronounced astrocytosis occurred in the three groups inoculated with the TME agent. In contrast, the neurohistological changes in the steers inoculated with the cattle-passaged scrapie agent were slight and subtle. Analysis of the octapeptide repeat region of the bovine protease-resistant protein (PrP) gene showed that variations in incubation period, clinical signs, and neurohistological changes were unrelated to the homozygous or heterozygous condition of six or six/five octapeptide repeats.

PMID: 8592050 [PubMed - indexed for MEDLINE]


The following research by USDA points to subclincal infection (positive for prion protein by immunohistochemistry) without obvious histologic changes indicative of spongiform encephalopathy (SE)

Cross-Species Transmission of Chronic Wasting Disease (Cwd-Mule Deer) to Domestic Livestock at the National Animal Disease Center (http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=149095):

Submitted to: American Association Of Veterinary Laboratory Diagnosticians
Publication Acceptance Date: October 9, 2003
Publication Date: October 9, 2003

Technical Abstract: To determine the transmissibility of chronic wasting disease (CWD) to cattle and sheep, 13 calves and 8 lambs were inoculated intracerebrally with brain suspension from mule deer (CWD-mule deer) naturally affected with CWD. Both investigations are currently in progress. The cattle experiment was started in 1997. Five and half years post inoculation (PI), 10/13 cattle have either died or were euthanized. Five of these were positive for prion protein (by immunohistochemistry). However, only the initial 2 cattle, euthanized at 23 and 24 months PI, had clinical signs (weight loss), and none revealed obvious histologic changes indicative of spongiform encephalopathy (SE). Three cattle remain alive and apparently healthy. The ovine experiment is 4 years PI and so far 2 sheep (both QQ at codon 171) have been euthanized. Only 1 had clinical signs and histopathologic lesions of SE that were indistinguishable from sheep scrapie, and the brain was positive for prion protein. Six remaining sheep (2 QQ and 4 QR at 171) are apparently healthy. These preliminary findings demonstrate that although the CWD-mule deer agent can be transmitted to cattle and sheep by intracerebral inoculation, an obvious neurologic manifestation of the disease is only seen in the latter species. These results also indicate that the diagnostic techniques currently used for bovine spongiform encephalopathy (BSE) surveillance would also detect the CWD agent in cattle and sheep should it occur naturally. Since intracerebral inoculation is an unnatural route for TSE infection, it has little bearing on the potential for cattle to become infected under natural conditions of exposure and these data may not reflect the situation seen after a natural infection.


Veterinarians question Transmissible Spongiform Encephalopathies (TSE) and infected feed as a link to CDS (Cognitive Disorder, Alzheimer's), the most common degenerative neurological disease in dogs and cats in the U.S.

Deer and Dog Spongiform Encephalopathy survey

Putative TSE in hounds - work started 1990 -(see para 41)

Robert Higgins, a Veterinary Investigation Officer at Thirsk, had been working on a hound survey in 1990. Gerald Wells and I myself received histological sections from this survey along with the accompanying letter (YB90/11.28/1.1) dated November 1990. This letter details spongiform changes found in brains from hunt hounds failing to keep up with the rest of the pack, along with the results of SAF extractions from fresh brain material from these same animals. SAFs were not found in brains unless spongiform changes were also present.

The spongiform changes were not pathognomonic (ie. conclusive proof) for prion disease, as they were atypical,being largely present in white matter rather than grey matter in the brain and spinal cord. However, Tony Scott, then head of electron microscopy work on TSEs, had no doubt that these SAFs were genuine and that these hounds therefore must have had a scrapie-like disease. I reviewed all the sections myself (original notes appended) and although the pathology was not typical, I could not exclude the possibility that this was a scrapie-like disorder, as white matter vacuolation is seen in TSEs and Wallerian degeneration was also present in the white matter of the hounds, another feature of scrapie.

Terry Singletary reviewed the literature on hound neuropathology, and discovered that micrographs and descriptive neuropathology from papers on 'hound ataxia' mirrored those in material from Robert Higgins' hound survey. Dr Tony Palmer (Cambridge) had done much of this work, and I obtained original sections from hound ataxia cases from him. This enabled me provisionally to conclude that Robert Higgins had in all probability detected hound ataxia, but also that hound ataxia itself was possibly a TSE. Gerald Wells confirmed in 'blind' examination of single restricted microscopic fields that there was no distinction between the white matter vacuolation present in BSE and scrapie cases, and that occurring in hound ataxia and the hound survey cases.

Hound ataxia had reportedly been occurring since the 1930's, and a known risk factor for its development was the feeding to hounds of downer cows, and particularly bovine offal. Circumstantial evidence suggests that bovine offal may also be causal in FSE, and TME in mink. Despite the inconclusive nature of the neuropathology, it was clearly evident that this putative canine 
spongiform encephalopathy merited further investigation.

The inconclusive results in hounds were never confirmed, nor was the link with hound ataxia pursued. I telephoned Robert Higgins six years after he first sent the slides to CVL. I was informed that despite his submitting a yearly report to the CVO including the suggestion that the hound work be continued, no further work had been done since 1991. This was surprising, to say the very least.

The hound work could have provided valuable evidence that a scrapie-like agent may have been present in cattle offal long before the BSE epidemic was recognized. The MAFF hound survey remains unpublished.

Transmissible Spongiform Encephalopathies

UK - European Commission CJD/BSE: TSE Guidance Note the Appendix includes:

Statement on ACDP/SEAC 

Part 1 - Introduction  (44kb) 
Part 2 - Health and Safety management of TSEs (35kb) 
Part 3 - Laboratory containment and control measures (156kb) 
Part 4 - Infection control of CJD and related disorders in the healthcare setting (62kb)

Annex A.1 - Distribution of TSE Infectivity in Human Tissues and Body Fluids (14kb) 
Annex A.2   Distribution of TSE infectivity in Animal Tissues and Body Fluids - see 1998 guidance, annex A 
Annex B - Diagnostic criteria (19kb) 
Annex C - Decontamination and waste disposal (179kb)
Annex D - Transport of TSE-infected material (98kb) 
Annex E - Quarantining of surgical instruments (9kb) 
Annex F - Decontamination of endoscopes (23kb)
Annex G - Decontamination of other specialised equipment (see 1998 guidance, annex B) 
Annex H - After death (25kb)

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