Listserve post from Kari Koester-Loesche
17 June 96:
In England especially, clusters of CJD were already known before there was BSE (Matthews, 1975). The 14 CJD deseases in India after a vaccination against rabies based on serum of sheep (in the Himalyan foothills, with scrapie in many flocks) are a clear indication of an infection.
In the USA, some CJD deseases were put down to the eating of brains of wild goats with scrapie. The 3 conjugal cases of CJD, described in the scientific literature, obviously argue in favour of an infection. Where from, before BSE?
Consider the fact that:
In fact, most cases of CJD so far were possibly causedby scrapie (notational suggestion: S-CJD by scrapie and B-CJD by BSE).
up to now, and with every single animal species, we don't know any other cause of TSE than an infection (so why not with human beings?).
sqirrels, having TSE, were blamed for being the cause of CJD.
scrapie and CJD, for instance, cause equal clinical signs in the goat, with different pathological-anatomical patterns of lesions.
brain lesions of BSE infected monkeys and men with V-CJD look strikingly similar.
On top of this, the unofficial numbers of 1500 - 9000 dead of CJD per annum in G.B. would correspond well with the high infection with scrapie. Considering moreover the U.S. spot check results, according to which about 5% of the Alzheimer diagnosises were misjudged CJD, the numbers of CJD worldwide probably look completely different. In my opinion, the number of 1 dead of CJD per million inhabitant has purely and simply never been checked.
As a whole, there are many indications of the infectiosity of scrapie in humans, but none speaking against. It's the same situation as with BSE until 19 March 1996.
RIVERDALE, Md. (May 13, 1996 9:48 p.m. EDT) - A British scientist said in Maryland on Monday he had proven that a common method of making animal feed was ineffective in destroying the agent that caused scrapie, a sheep disease similar to so-called mad cow disease.
Researcher David Taylor of Edinburgh University said he took brain matter from scrapie-infected sheep, subjected it to a rendering process and injected it into the brains of mice. Many of the mice then contracted a similar disease, he said.
Scientists say waste sheep parts that were cooked in a process known as rendering and used in animal feed were probably responsible for starting the mad cow epidemic in Britain in the 1980s.
Cattle parts were also rendered and used in feeds, contributing to the spread of the disease in cattle, scientists have said.
Taylor, principal research scientist at Edinburgh's neuropathogenesis unit, told a public meeting here on mad cow disease, formally known as Bovine Spongiform Encephalopathy (BSE), that he reproduced several different rendering processes in his laboratory trials. None of the processes stopped the infectivity completely, he said.
Taylor said he would publish them soon. He and other researchers published similar results in December from an experiment using brains from cattle infected with BSE.
The practice of feeding ruminant, or cud-chewing animals such as sheep and cattle, with protein meal made from other ruminants was banned in Britain in 1988, eventually leading to a sharp decline in the number of BSE cases there.
This year, the British government extended the ban to exclude ruminant protein from feed intended for all animals. The additional safeguard was introduced after the government said there was a possible link between BSE and some recent cases of Creutzfeldt Jakob Disease in people.
Copyright © 1996 Nando.net
Copyright © 1996 Reuter Information Service
The only link with BSE between species ever discovered is in animal feed made from ground-up sheep. This feed is blamed for Britain's BSE epidemic in cows - and even for several dozen deaths of house cats.
What about using sheep to make animal feed?
Britain has banned the practice, but sheep still make up about two-tenths of a percent of the animals ``rendered'' into U.S. feed, said Don Franco of the National Renderers Association. But no more than 50 cases of scrapie a year are found in the nation's 8.9 million sheep, meaning it's unlikely that U.S. animal feed could be tainted, Detwiler said.
This infectious disease is thought to be most commonly spread from ewe to offspring and to other lambs in contemporary lambing groups through contact with placental fluids. Signs or effects of the disease do not usually appear until 2 to 5 years after the animal is infected. Once an animal becomes infected, death is inevitable. There is no test to detect scrapie in a live animal.
In the United States, scrapie has primarily been reported in the Suffolk breed. It also has been diagnosed in Cheviots, Corriedales, Dorsets, Hampshires, Finn sheep, Merinos, Montadales, Southdowns, a Cotswold, a Rambouillet, and a number of crossbreeds. As of January 1993, four cases of scrapie in goats raised in contact with sheep have been reported. First recognized as a disease of sheep in Great Britain and other countries of Western Europe more than 250 years ago, scrapie has been reported throughout the world. The only two countries recognized as being free of scrapie are Australia and New Zealand.
The first case of scrapie in the United States was diagnosed in a Michigan flock in 1947. These sheep were of British origin, imported from Canada over a period of several years. Through September 1992, scrapie had been diagnosed in at least 652 flocks in the United States.
Over the years, scrapie has been officially reported in 42 States. As of September 1992, States with no reported cases were Alaska, Arizona, Arkansas, Rhode Island, Florida, Hawaii, Montana, and North Dakota.
Without a screening test for sheep, the incidence of scrapie cannot be accurately determined. Reporting the disease usually requires knowledge about scrapie and its signs and the willingness to make known a problem. Since 1947, from 1 to 54 flocks have been reported as newly infected every year.
Researchers have been studying scrapie for many years to identify the specific agent that causes it. The agent is smaller than the smallest known virus and has not been identified to date. To complicate matters further, this disease agent is extremely resistant to heat and ultraviolent irradiation as well as to various disinfectants--the common means of destroying pathogens. In its host, the agent elicits no inflammatory or specific immune response.
Genetic variations among different breeds and the strain of scrapie may play a role in whether a sheep will become infected and how quickly clinical signs of scrapie may appear. One gene that controls the length of incubation of clinical scrapie has been identified in Cheviot and Swaledale sheep. Those individuals with "short" incubation alleles (alternative forms of a gene) develop the clinical signs, usually between 2 and 5 years of age. These sheep die from what appear to be natural causes before the incubation period is complete. Because the length of incubation can be as long as 8 years, it is not known to what extent or under what conditions sheep with the "long" incubation alleles might be able to infect other sheep. The strain of scrapie also appears to affect the development of clinical signs and the length of the incubation period.
Scrapie signs vary widely among individual animals and develop very slowly. Early signs include subtle changes in behavior or temperament, which may be followed by scratching and rubbing against fixed objects--apparently to relieve itching. Other signs are loss of coordination, weight loss despite retention of appetite, biting of feet and limbs, lip smacking, and gait abnormalities--including high-stepping of the forelegs, hopping like a rabbit, and swaying of the back end.
An infected animal may appear normal if left undisturbed at rest. However, when stimulated by a sudden noise, excessive movement, or the stress of handling, the animal may tremble or fall down in a convulsive-like state. Every infected animal may not show every sign. Sheep may live from 1 to 6 months or longer after the onset of clinical signs.
Several other problems can cause scrapie-like signs in sheep, including the diseases ovine progressive pneumonia, listeriosis, and rabies; the presence of external parasites (lice and mites); pregnancy toxemia; and toxins.
Some diseases related to scrapie affect other species as well. Kuru and Creutzfeldt-Jakob disease affect humans; transmissible mink encephalopathy affects mink; feline spongiform encephalopathy affects cats; chronic wasting disease affects mule deer and elk; and bovine spongiform encephalopathy (BSE) affects cattle. In the laboratory, scrapie has been transmitted to hamsters, mice, rats, gerbils, mink, and some species of monkeys.
In the field, veterinarians diagnose scrapie based on the appearance of its signs combined with knowledge of the animal's history. At present, scrapie can be confirmed only by microscopic examination of brain tissue at necropsy. There is no officially recognized test for the presence of scrapie in live animals. Currently, researchers at the APHIS National Veterinary Services Laboratories are working to develop a more efficient and definitive postmortem test using immunoblotting and immunohistochemistry.
Other research efforts are presently focused on developing a practical, live-animal test to diagnose infected sheep before they show signs; transmissibility of the disease; identifying the scrapie agent and its different strains; identifying genes that control incubation length; and examining the role of artificial insemination and embryo transfer in the transmissibility of scrapie.
In 1952, the Secretary of Agriculture declared a state of the emergency in an attempt to eradicate scrapie in the United States. This order was rescinded in 1953, and USDA put a total flock depopulation program into effect. In 1957, the program was expanded to include total depopulation of source flocks. USDA's scrapie and bloodline indemnification and surveillance program was implemented on April 8, 1983.
The bloodline indemnification program was discontinued on January 8, 1993, and was replaced by a one-time-only indemnity payment for qualifying producers with infected or source flocks reported to USDA by July 7, 1993. The Voluntary Scrapie Flock Certification program began on October 1, 1992. The voluntary program is a cooperative effort between producers, allied industry representatives, accredited veterinarians, State animal health officials, and USDA's Animal and Plant Health Inspection Service (APHIS).
The intent of the voluntary program is to monitor flocks over a period of 5 years or more and to identify flocks that are free of scrapie. The program provides participating producers with the opportunity not only to protect their sheep from scrapie but also to enhance the marketability of their animals. Flock owners may apply for membership in the program by sending a written request to their State's Scrapie Certification Board. It will require cooperation among producer organizations, allied industries, and government regulatory agencies to operate an effective program to deal with this insidious disease.
A cellular form of the prion protein (PrPC) is thought to be a substrate for an abnormal isoform of th eprion protein (PrPSc) in scrapie. PrPC is abundant in tissues of the central nervous system, but little is known about the distribution of PrPC in non-neuronal tissues of sheep, the natural host of scrapie. This study investigated the tissue distribution of PrPC in sheep. Although PrPC was abundant in neuronal tissues, it was detected in non-neuronal tissues such as spleen, lymph node, lung, heart, kidney, skeletal muscle, uterus, adrenal gland, parotid gland, intestine, proventriculus, abomasum and mammary gland. Neither PrPC nor PrP mRNA was detected in the liver. The tissue distribution of PrPC appears to be inconsistent with the tissues which possess scrapie infectivity, suggesting that factor(s) specific to certain cell types may be required to support multiplication of the scrapie agent.
The authors studied ten years of the records of a sheep flock in which scrapie was endemic. Each year, 50% had been sold for meat and 30% for breeding. Scrapie had appeared in 20% of the sheep retained on the farm. The aim of the study was to discover if eating meat from scrapie sheep produced Creutzfeldt-Jakob disease in humans, but the work threw no light on this.
A letter followed by five others on the same subject by H. Diringer, L.R. Bridges, H. Fraser, J. Hardy and A. Goate, and S.C. Arya. The correspondence by S.C. Arya suggests the cases of Creutzfeldt-Jakob disease in India may have resulted from scrapie in rabies vaccine made from sheep's brain.
The author recommends a mandatory histological screen for scrapie in a proportion of sheep (10-20%) in all flocks used to produce sheep-brain rabies vaccine to prevent the spread of viruses which can cause spongiform encephalopathies in India.
Supernatant fluid from a scrapie-infected hamster brain homogenate was mixed with soil, packed into perforated petri dishes that were then embedded within soil-containing pots, and buried in a garden, in the Washington DC area, for 3 years. Between 2 and 3 log units of the input infectivity of nearly 5 log units survived this exposure, with little leaching of virus into deeper soil layers. These results have implications for environmental contamination by scrapie and by similar agents, including those of bovine spongiform encephalopathy and Creutzfeldt-Jakob disease.
In the August 29, 1994, Federal Register, FDA proposed a rule to prohibit specified offal from adult (more than 12 months of age) sheep and goats for use in ruminant feed. FDA is proposing this action because the specified offal may contain the agent that causes scrapie, a transmissible spongiform encephalopathy (TSE) of sheep and goats. In the United Kingdom, scrapie has been epidemiologically associated with the occurrence of bovine spongiform encephalopathy (BSE), another TSE.
Faure did not eat beef but frequently ate lamb. Scrapie has been present in Willamette Valley sheep flocks; recently, an entire flock of 140 animals was voluntarily destroyed by its owner. Fauve's widow was familiar with CJD because the mother of a man in her office had also died from it.
There is an anecdotal account that may be useful. A team of veterinary researchers working somewhere at a field laboratory in rural Scotland during the 1950s was followed up around 1980 to determine health outcomes and/or reasons for death. The results seemed at the time to be astounding. As I recall, something like 3 of 10 people had gone on the develop CJD.
And the disease they had been studying? - Scrapie.
Prof. Tim Sly
School of Environmental Health
Ryerson Polytechnic University
Toronto, Ontario, Canada
AFRICA:*It is interesting to note that before Switzerland set up their active surveillance programme for livestock neurologic diseases in 1990, they only suspected scrapie. It was immediately found in 1990 in some number.
Ghana, last reported case seen in 1993 South Africa, last reported case 1972
Brasil, last reported case 1985 Canada, one flock slaughtered for scrapie in P. Ontario, a second in P. Quebec. USA, low sporadic rate, voluntary scrapie free flock certification program since 1 Oct 1992.
The first case of scrapie in the United States was diagnosed in a Michigan flock in 1947. These sheep were of British origin, imported from Canada over a period of several years. Through September 1992, scrapie had been diagnosed in at least 652 flocks in the United States. Scrapie has been officially reported in 42 States.
Cyprus, low sporadic rate Japan, low sporadic rate,last reported in 1994
Belgium, last reported in 1992 Czech Rep., sporadic France, sporadic Germany, last reported in 1990 Iceland, sporadic Ireland, sporadic Sweden, last reported in 1986 Switzerland, last reported in 1993* UK, enzootic
Australia, last reported in 1952 New Zealand, last reported in 1954
Peiffer, J. : Gerstmann-Straussler's disease, atypical multiple sclerosis and carcinomas in a family of sheepbreeders. Acta Neuropath. 56: 87-92, 1982.Peiffer (1982) described a family of sheepbreeders in which a father and 2 sons had GSD. All 3 also had congenital hip dysplasia, as did at least 3 other members of the kindred, all females. Atactic symptoms, dysarthria, and personality changes characterized the clinical course of this disorder, which might be labeled atypical multiple sclerosis.
Like CJD , GSS is a form of subacute spongiform encephalopathy. Cases of GSS are clinically similar to the atactic type of CJD. Although there are many neuropathologic similarities, GSS differs from CJD by the presence of kuru-plaques and numerous multicentric, floccular plaques in the cerebral and cerebellar cortex, basal ganglia, and white matter. Whereas only 5 to 15% of CJD cases are familial, most cases of GSD are familial.
NZ Veterinary Correspondent
Tue, 2 July 1996
"In both scrapie epsiodes in New Zealand, one in the fifties and the other in 1974, the sheep never make it to the mainland. New Zealand has a quarantine island off the coast and when the scrapie was identified, all the sheep were eradicated before they ever set foot off the island. That's why we can say with confidence, New Zealand does not have scrapie.
New Zealand, as a result of its physical isolation, is free of prion disease. It is vital that serum products will be beyond question. Most people don't realize their vaccines have been cultured on bovine serum products and therefore the potential for exposure to BSE, or pestivirus (BVD) is far greater than the current thinking of ingestion being the only way in which to acquired disease.
Also related: Icelandic sheep pasture being rested for 3 years, scrapie-free herd introduced and getting it. Sheep contracting scrapie in Iceland after 3 years of rested pasture was no surprise after the repeat episode with CWD in the game parks. How long prion infectious agent can persist was always the question. Fleas is an interesting one. As you are aware, the research in Iceland identified the scrapie prion in the bodies of sheep mites. The situation would be identical for fleas."
Adapted from Steven Dealler's site
Scrapie in the USA
USDA:APHIS:VS, 1990: "Quantitative analysis of BSE risk factors in the US"
USDA:APHIS:VS, 1993: "BSE: Implications for the US"
Sheep farm size and concentration of sheep92,000 sheep operations in US
10,585,000 sheep (7,521,000 greater than 1 year old)
So 115 sheep per operation, on average (ie, many small hobby operations)
More money paid to reimburse rancher = more reported scrapie:Inflation in the level of compensation seemed to have to most effect on the number of sheep reported with scrapie. This was clearly seen when the indemnity was raised to $300 in 1977. In the 8 years after this the scrapie numbers went up 10 fold and, as the level of indemnity inflated downwards, the numbers reported gradually fell. The numbers were not as individual sheep but rather in the number of flocks reported, which hit an annual peak of around 50 flocks per annum.
Geographic distribution of scrapie within US:This appears to follow the distribution of sheep. The enormous excess of Suffolk breed of sheep (84%), a breed that is known to be prone to scrapie in the UK, makes this finding not surprising.
Number and age of sheep slaughtered annually (1989) in US and UK
USA UK All sheep slaughter 5,225,000 18,398,000 Mature sheep 347,000 1,940,000 Slaughter ratio lamb to ewe 15 9.5