Press Release WHO/28

3 April 1996

International Experts Propose Measures To Limit Spread Of BSE And Reduce Possible Human Risks From Disease

At a consultation organized by the World Health Organization (WHO) in Geneva on 2-3 April 1996, a group of international experts reviewed the public health issues related to bovine spongiform encephalopathy (BSE) and the emergence of a new variant of Creutzfeldt-Jakob Disease (CJD), as officially reported by the United Kingdom (UK) on 20 March 1996.

The consultation made recommendations, based on the latest scientific information, to minimize transmission of BSE among animals and to reduce as completely as possible any exposure of humans to the BSE agent.

Findings of the Consultation

Bovine Spongiform Encephalopathy:

BSE is a transmissible spongiform encephalopathy (TSE) in cattle which was first identified in the United Kingdom in 1986. It is one of a group of similar degenerative diseases which occur in several animal species. Transmission of BSE to cattle appears to have been via contaminated meat and bone meal in concentrate feed, with sheep or cattle being the original source. The UK is the only country with a high incidence of the disease, and the epidemic there appears to have been due mainly to recycling of affected bovine material back to cattle before the ruminant (cattle, sheep and goats) feed ban in July 1988 took effect. There is no evidence to date of either maternal or horizontal transmission of BSE.

The incidence of the disease is declining significantly in the UK, although the measures introduced have not thus far halted the epidemic. The worldwide distribution of BSE is not known precisely, but it has been reported at a much lower incidence than in native cattle in other European countries. In these latter countries only part of the BSE cases could be related to consumption of possibly BSE-contaminated feed.

Variant Creutzfeldt-Jakob Disease (V-CJD):

The group reviewed the clinical and pathological data from the 10 cases in the UK. The disease has occurred at younger ages than is usual for classical CJD and shows several clinical and pathological differences. Based on findings in these 10 cases, the group established a case definition to facilitate better surveillance, which is necessary to determine the incidence and distribution of this syndrome.

The group concluded that there is no definite link between BSE and V-CJD, but that circumstantial evidence suggests exposure to BSE may be the most likely hypothesis. Further research on both diseases is urgently required.

Exposure to BSE has already been greatly reduced by measures taken in the UK. Implementation of the recommendations by this consultation should further reduce risk from exposure to BSE to minimal levels.

Recommendations

Bovine Spongiform Encephalopathy:

1. No part of any animal which has shown signs of TSE should enter any food chain, human or animal. All countries must ensure the slaughter and safe disposal of TSE-affected animals so that TSE infectivity cannot enter any food chain. All countries should review their rendering procedures to ensure that they effectively inactivate TSE agents.
2. All countries should establish continuous surveillance and compulsory notification for BSE according to recommendations established by the Office International des Epizooties in Paris. In the absence of surveillance data, the BSE status of a country must be considered as unknown.
3. Countries where BSE exists in native cattle should not permit tissues that are likely to contain the BSE agent to enter any food chain, human or animal.
4. All countries should ban the use of ruminant tissues in ruminant feed.
5. With respect to specific products:
   • Tests on milk from BSE-infected animals have not shown any BSE infectivity, and there is evidence from other animal and human spongiform encephalopathies to suggest that milk will not transmit these diseases. Milk and milk products, even in countries with high incidence of BSE, are therefore considered safe.
   • Gelatin is considered safe for human consumption since its preparation involves a chemical extraction process that destroys BSE infectivity.
   • Tallow is likewise considered safe if effective rendering procedures are in place.
6. With respect to medicinal products, which differ from food in that they can be injected as well as taken orally, measures to minimize the risk of transmitting the BSE agent were developed at a previous WHO consultation in 1991 and continue to be applicable.
   • As more information becomes available these measures will be reviewed and strengthened if necessary.
   • The importance of obtaining materials destined for the pharmaceutical industry from countries which have a surveillance system in place and which report either no or sporadic cases of BSE is reiterated.
   • Removal and inactivation procedures contribute to the reduction of the risk of infection. But it must be recognized that the BSE agent is remarkably resistant to physico-chemical procedures which destroy the infectivity of common microorganisms.
7. Research on TSE should be promoted, especially on rapid diagnosis, agent characterization, and epidemiology of TSEs in humans and animals.

Variant Creutzfeldt-Jakob Disease (V-CJD):

1. The geographic distribution of V-CJD, although reported at present only in the UK, needs to be further investigated.
2. While the most likely hypothesis at present for this newly recognized variant is exposure to the BSE agent, further data from scientific studies on these variant cases are urgently required to establish a link. More monitoring and surveillance studies on all forms of CJD are required throughout the world, modelled on current European collaborative studies.
3. Exposure to BSE from beef and beef products has already been substantially reduced by the measures taken in the UK. Exposure to BSE has always been lower in other countries. The group considered that implementation of their recommendations will ensure that any continuing risk of exposure to BSE in beef and beef products will be reduced to a minimum.

As surveillance worldwide is increased for both BSE and V-CJD, more information will become available in the coming months. WHO will keep these developments under review and update the recommendations as appropriate.

For further Information, please contact:

Philippe Stroot
Media Relations, Health Communications and Public Relations, WHO, Geneva,
tel. (41 22) 791 2535
fax (41 22) 791 4858
E-mail: strootp@who.ch

or

Dr David Heymann
Director, Division of Emerging and other Communicable Diseases Surveillance and Control, WHO, Geneva.
Tel. (4122) 791 2660
Fax (41 22) 791 4198
E-mail: heymannd@who.ch

All WHO Press Releases, Fact Sheets and Features can be obtained on the WHO home page http: //www.who.ch/

end of WHO statement.

J Ralph Blanchfield

Food Science, Food Technology & Food Law Consultant Chair, IFST Member Relations & Services Committee

Web Editor, Institute of Food Science & Technology

IFST Web address: http://www.easynet.co.uk/ifst/