Biomedical subjects

Ray Bradley

Publications and source records attributed to Ray Bradley.

6 recordsLinked to original sources

PubMed2006

Variant CJD (vCJD) and bovine spongiform encephalopathy (BSE): 10 and 20 years on: part 1.

From 1986 more than 184,000 cattle in the UK and islands (of which >1,880 have been detected by active surveillance using rapid tests) and approaching 5,500 elsewhere have been confirmed with BSE. The original 1988 ban on the use of ruminant-derived protein in ruminant feed has been upgraded and now prohibits the use of any processed animal protein in feed for any farmed food animal. As a result of rigorous enforcement this reinforced ban is now regarded as fully effective from 1 Aug. 1996. Reasons are given for the substantial slippage that occurred initially and for the small but diminishing number of cases that have occurred in cattle born after 1 Aug. 1996. The 1989 offal ban, initially introduced to protect public health, has likewise been progressively strengthened and since 1995 has been effectively enforced by the Meat Hygiene Service, thus protecting the consumer. It is now extended as the specified risk material (SRM) ban throughout the EU. BSE continues to decline towards elimination in the UK and is being dealt with effectively in other Member States of the European Union (EU) and Switzerland with an extensive (and very expensive) range of edicts. The improving situation in the EU has encouraged the EC to draft a TSE Roadmap outlining possible reduction in control measures whilst still protecting the consumer. The situation on a global basis still causes concern as, although cases are less frequent than in the UK, surveillance, legislation and enforcement are not clearly as extensive and effective as in the EU. The risk of primary transmission of BSE to man from cattle to cause variant CJD (vCJD) is examined with reference to up-to-date assessments of bovine tissue infectivity and is now regarded as unlikely in the EU and Switzerland.

Animal Feed↗

PubMed2006

Variant CJD (vCJD) and bovine spongiform encephalopathy (BSE): 10 and 20 years on: part 2.

Up until February 2006, variant CJD (vCJD), the human disease associated with transmission of BSE from cattle, has been confirmed in 160 patients resident in the UK and 28 elsewhere, some of whom have never visited the UK. Cases have been reported in France (16 cases), Ireland (3), USA (2), Canada, Italy, Japan, The Netherlands, Portugal, Saudi Arabia and Spain (1 each). The presumed main period of hazard for ingestion of the BSE agent in bovine products in the UK is 1984-89, or perhaps up to 1995-6 but at a reduced level. Debated incubation periods for vCJD are discussed, with special reference to the wide, but currently reducing, range of predicted further primary cases in the UK. The primary disease seems to be preferentially acquired by, and expressed in, relatively young people. All but one of the British cases examined so far were homozygous for methionine at the polymorphic codon 129 of the prion protein PRNP gene. Tests of appendix specimens from large numbers of otherwise normal subjects at the time of appendicectomy have revealed lymphoreticular accumulations of PrP(Sc) in a few samples. Furthermore, three patients who died of vCJD had appendices removed by appendicectomy whilst healthy. Two of these appendices were retrospectively shown to be positive for PrP(Sc) and one removed 10 years before clinical onset was negative. This has led to worries regarding the possibility of pre-clinical or sub-clinical prion-associated disease in an unknown proportion of the population. To date, there has been no known association of primary vCJD with occupation, medicines, immunising agents, gelatine, or surgery (including the use of catgut sutures), or exposure to bovine products other than by ingestion. There is much concern that human-to-human (secondary) vCJD infection is transferred by blood transfusion. A possible risk is also perceived from infected blood products, human organs and tissues, or via contaminated surgical instruments or devices though, so far as is known, no cases have yet arisen in this way. Steps have been taken to reduce the risks and much research is in hand in this field. Continued TSE surveillance, the maintenance of adequate preventive controls, attention to possible parenteral challenges, and further research studies are of paramount importance.

Animals↗

PubMed2004

Bovine spongiform encephalopathy (BSE): the end of the beginning or the beginning of the end?

Bovine spongiform encephalopathy (BSE) is a zoonosis being the origin of variant Creutzfeldt-Jakob disease and an important cattle disease in its own right. This association has driven both the research into the disease and extensive epidemiological investigations of practical value. Not only has the occurrence of BSE has a serious effect on animal health and public health, it has also seriously interrupted trade in cattle and cattle products from affected countries. Since 2001, several additional European countries, Japan, Israel and Canada have reported BSE in native-born stock and this has led to a concern about the BSE status of countries that have imported cattle and cattle products from any affected country. A single case recently reported in the USA was in a cow imported from Canada, thus extending the risk of BSE occurrence into the North American continent as a whole. Extensive feed and offal bans have protected the food and feed chains in all countries with BSE, even though initially they tended to be leaky. Application of newly-developed, approved 'Rapid' tests for misfolded PrP in central nervous tissue of targeted, high-risk animals and slaughter cattle now provides the tools whereby the real incidence of the disease (and to a degree, infection) can be determined in an active surveillance programme. 'Rapid' testing also enables the progress of epidemics to be monitored in response to applied measures. In the EU, over 10 million cattle are tested annually. Analysis of the extensive data shows that it is the beginning of the end of the BSE epidemic in the UK; most European countries, Israel and Japan are close behind. The epidemic in North America (two cases to date) is at the beginning. Significant measures had already been adopted there to reduce the risk from recycling of infection via feed but it remains to be seen if they are watertight. Advice has been given to ensure that public health is protected and to monitor the epidemic by strategic use of approved 'Rapid' tests to determine that the epidemic is in fact trivial as believed, or otherwise to identify weaknesses in measures that can be corrected. It is imperative that all countries conduct risk assessments for BSE, follow the OIE recommendations and do not unreasonably disrupt international trade. There is a responsibility for all countries with BSE to ensure that infection is not exported to any country, particularly through live cattle and especially via meat-and-bone-meal, which is the acknowledged vehicle of transmission. There is also a responsibility placed upon all countries to protect, not only their cattle populations, but also their human populations from exposure to this economically important fatal disease. If all the advice is taken and measures enforced there is a prospect that BSE can be eliminated from countries and regions as a prelude to eradication from the world.

Animals↗

PubMed2003

Bovine spongiform encephalopathy (BSE) and its epidemiology.

Since the recognition of BSE in 1986, over 180,000 cattle in the UK have developed the disease and 1-3 million are likely to have been infected with the BSE agent, most of which were slaughtered for human consumption before developing signs of the disease. The origin of the first case of BSE is unknown, but the epidemic was caused by the recycling of processed waste parts of cattle, some of which were infected with the BSE agent, to other cattle in feed. Control measures have resulted in the consistent decline of the epidemic in the UK since 1992. Cattle and feed exported from the UK have seeded smaller epidemics in other European countries, where control measures were applied later. If the control measures now in place to protect public and animal health are well enforced, the epidemic in cattle should be largely under control and any remaining risk to humans through the consumption of beef should be very small.

Animal Feed↗

PubMed2002

Bovine spongiform encephalopathy. Update.

Bovine spongiform encephalopathy (BSE) is a zoonosis being the origin of variant Creutzfeldt-Jakob disease and an important cattle disease in its own right. Countries have been slow to learn the importance of protecting, not only their cattle populations, but also their human populations. Since 2000, several additional European countries have reported BSE in native-born stock and this has led to a concern about the BSE status of countries that have imported cattle and cattle products from infected countries. Extensive feed and offal bans and application of newly-developed, 'Rapid' tests for prion protein in central nervous tissue of targeted, high-risk animals and slaughter cattle over 30 months old now provides the tools whereby the public are fully protected and BSE can be eradicated.

Animals↗

PubMed2002

Bovine spongiform encephalopathy update.

Bovine spongiform encephalopathy (BSE) is a zoonosis being the origin of variant Creutzfeldt-Jakob disease and an important cattle disease in its own right. Countries have been slow to learn the importance of protecting, not only their cattle populations, but also their human populations. Since 2000, several additional European countries have reported BSE in native-born stock and this has led to a concern about the BSE status of countries that have imported cattle and catlle products from infected countries. Extensive feed and offal bans and application of newly-developed, "Rapid" tests for prion protein in central nervous tissue of targeted, high-risk animals and slaughter cattle over 30 months old now provides the tools whereby the public are fully protected and BSE can be eradicated.

Animals↗