BSE and vCJD: Their biology and management
BSE and vCJD: Their biology and management

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BSE and vCJD: Their biology and management

10 Managing the BSE/vCJD episode from March 1996

In March 1996, SEAC announced that the CJD Surveillance Unit had identified vCJD as a new human disease, the first death from which occurred in May 1995. SEAC concluded that, although there was no direct evidence of a link, the most likely explanation for vCJD was exposure to BSE before the SBO ban was introduced in 1989. At the time, the strongest evidence for the link was that vCJD was a new TSE in humans (the symptoms of which differed from previously known human TSEs) that had arisen about a decade after BSE, a new TSE in cattle. As we know from earlier in the course, the link was confirmed only later through similarities between the conformation of the PrPSc molecules in humans with vCJD and in cattle with BSE. [C]

The Secretary of State for Health made a formal statement about the likely link between BSE and vCJD in the House of Commons on 20 March 1996. Confirmation that there was almost certainly a link between BSE and vCJD ('the human form of mad cow disease') - despite repeated assurances over the years from politicians, officials such as the CMO and public bodies such as SEAC - represents a dramatic turning point in the BSE story. Of course, there was extensive media coverage of this development. Public confidence in the safety of British beef was severely dented and sales of beef and beef products fell dramatically. The price of beef products in the shops also fell, as attempts were made to stabilise the market. [C R D]

Question 51

Was it right to encourage people to buy food that might not have been entirely safe by offering it at bargain prices? [R E]

Answer

By 1996, after a whole series of precautionary measures had been introduced to safeguard public health, managers in the retail trade were presumably completely convinced that beef was perfectly safe to eat. On the other hand, they would also be acutely aware that many people's livelihoods (including their own to some extent) would be jeopardised if the beef industry were allowed to collapse.

At the same time, the government also announced a further precautionary measure - again following advice from SEAC - that cattle over 30 months old had to be deboned at specially licensed plants and the trimmings kept out of the food chain (this was known as the 30+ months ban). Furthermore, mammalian MBM was to be banned in all feed for farm animals (i.e. not only feed intended for ruminants or even mammals). [R D]

Question 52

What do these two measures suggest?

Answer

The first suggests that the authorities considered that cattle older than 30 months might pose a greater risk to humans than younger cattle. The second suggests that the authorities suspected that feed intended for non-ruminant farm animals (e.g. chickens) might be being eaten by cattle and other ruminants.

Also in March 1996, the EC prohibited export from the UK of live bovine animals; bovine semen and embryos; the meat of bovine animals slaughtered in the UK; products of bovine animals slaughtered in the UK liable to enter the food chain or destined for use in medicinal products, cosmetics or pharmaceutical products; and mammalian-derived MBM. In short, the EU banned all British beef exports (the beef export ban). A major priority of the UK government over the next few years would be to convince fellow members of the EU that sufficient measures had been taken to ensure that infected materials could not enter the human food chain. The success or otherwise of this campaign would, of course, be judged by the lifting or continuation of the EU ban. [D]

Not surprisingly, there followed a whole series of new and amended Orders and Regulations in the UK, most of which were designed to tighten up existing controls. Several of these were related to the decision that animals over 30 months old at the time of slaughter should not be allowed to enter the human food or animal feed chains. [D]

Question 53

What would be the scientific rationale for this? [R]

Answer

It was believed that most animals that contracted BSE did so as a result of consuming contaminated feed as calves. Because SBO had already been officially banned from cattle feed for many years by the mid-1990s, the probability of vCJD being transmitted to humans or BSE to other cattle should by then have been very low. Like all TSEs, BSE has a moderately long incubation period (typically 3-5 years) and so infected cattle were thought not to contain much PrPSc until they were over three years old. By ensuring that no animals older than 30 months entered the human food or animal feed chains, the ban should have reduced the risk even further.

A politically astute aspect of the 30+ months ban is that 'best beef' is eaten at less than 30 months old anyway. The ban was therefore designed to have the minimum possible adverse effect on the 'best beef' industry. Remember that BSE was largely a problem of dairy cows that were usually sent for slaughter when their milk yields declined after the age of five years.

Ministers announced in December 1996 that the backlog of animals that had to be slaughtered and disposed of under the 30+ months ban had been cleared.

Question 54

In the latter half of 1996, the Feed Recall Scheme was launched with the aim of collecting and disposing of any MBM and feed containing MBM present on farms, in feed mills or at feed merchants. To what extent do you think that this was appropriate? [R D]

Answer

Given that it had long been believed that BSE had been caused by contaminated feed and that it was known that some cattle born after the introduction of the SBO ban had developed BSE, recalling potentially contaminated feed was an appropriate course of action. However, it does seem rather surprising that such a scheme had not been organised much earlier. Presumably, the emergence of vCJD had convinced officials that this additional precaution was now urgently necessary. In effect, this measure removed decision making from the local level - farmers cannot accidentally or deliberately use MBM-containing feed if they don't have access to it.

The system of record keeping in the beef and dairy industries was enhanced considerably. For instance, from January 1999 one ear tag had to be permanently attached to a calf within 36 hours of birth and a second within 30 days. All cattle born from July 1996 also had to have mandatory cattle movement documents (so-called 'cattle passports'). Northern Ireland, which is particularly reliant on its beef exports, introduced at a relatively early stage a sophisticated and comprehensive computerised system for tracing animals. The existence of this system convinced the EC to lift the ban on beef exports from Northern Ireland more than a year before it decided to lift the ban on exports from the rest of the UK. [C D]

Question 55

What were the benefits of introducing such enhanced record keeping?

Answer

First, it should help ensure that cattle older than 30 months did not enter the human food chain. Secondly, when an animal was discovered to have BSE, possible sources of infection on the farm on which it was raised could be investigated and other animals that might have been infected at the same time could be traced for examination.

In May 1996, within two months of the announcement on vCJD, the UK government sent to the EC details of its BSE Eradication Programme, which was approved in principle the following month. At about the same time, the European Council meeting in Florence agreed a framework for lifting the ban on beef exports from the UK. This framework specified five preconditions that the UK was required to meet. One of these was implementation of a selective cull of cattle deemed to be most at risk of developing BSE. The UK government announced details of this selective cull in August 1996. However, following publication in Nature of the results of a major epidemiological survey by a team lead by Professor Roy Anderson of Imperial College London which suggested that the BSE epidemic would virtually die out around 2001 even if no further measures were taken, the UK government announced a month later that it would not be proceeding immediately with the cull. The reason given for this decision was that further scientific research needed to be done to establish the most appropriate culling strategy in the light of both the recent epidemiological study and preliminary results from MAFF (confirmed by SEAC in April 1997) which suggested some degree of cow-to-calf transmission of BSE. Such cow-to-calf transmission might represent genetic susceptibility to acquire infection from feed or transmission of the infectious agent through either the placenta or milk. In fact, the data suggest (but do not prove) the genetic explanation. Nevertheless, it was announced in December 1996 that the selective cull would go ahead after all and an Order to this effect came into force in January 1997 (along with another that dealt with the compensation to be paid for animals slaughtered under the cull). [C R D]

Question 56

Do these developments suggest there was a strong scientific basis for the cull? [R D]

Answer

No. It appears that the selective cull was mainly a precautionary measure designed to reassure the rest of the EU as part of the UK government's continuing effort to get the beef export ban lifted.

In parallel with the cull, the Date-Based Export Scheme (DBES) was developed in the hope that the ban on beef exports would be lifted from herds that were certified as having been BSE-free for a certain period of time.

The General Election in May 1997 brought Labour to power in the UK, with a huge majority in the House of Commons, after 18 years of rule by the Conservatives. The new administration continued to work towards persuading the EU to lift its ban on beef exports. [C]

Following a review conducted by MAFF and the Department of Health, in September 1997 the UK government confirmed that SEAC still had a key role to play in advising on BSE and vCJD. Shortly after announcing in October 1997 that it believed no further measures governing beef or beef products for human consumption were necessary, SEAC recommended that all beef derived from home-produced or imported cattle over six months old at slaughter should be deboned before sale to consumers. So-called 'beef on the bone' was banned from December 1997. The issue of beef on the bone then became something of a cause célèbre through 1998 and 1999 as politicians (mainly from opposition parties) and others took advantage of 'photo opportunities' to deliberately flout the ban in order to demonstrate their conviction that 'British beef was safe to eat'. They were certainly not taking an approach based on the precautionary principle. Rather, they challenged official decision makers through publicity stunts - a form of 'direct action'. Although the CMO advised in February 1999 that the ban should continue, it was finally lifted in December of that year. [C R E D]

The beef export ban was far more significant economically than the issue of 'beef on the bone'. In May 1998, the European Court of Justice upheld the validity of the ban on UK beef. However, the export ban was lifted for Export Certified Herds Scheme beef from Northern Ireland in June 1998. Then, from August 1999, the export ban was lifted for DBES beef from the whole of the UK. The French Food Standards Agency immediately expressed its concerns about the safety of British beef and France declined to lift the ban. The EC's Scientific Steering Committee unanimously concluded that it did not share these concerns about beef and beef products exported under DBES. In November 1999, the UK formally asked the Commission to take action against France for refusing to lift its ban and later that month the Commission asked the French government to review its decision. During December, the French government stated its intention to retain the ban. The Commission then issued a Reasoned Opinion (a legal device) on France's failure to lift the ban, which France responded to by insisting that it would maintain the ban. Finally, the Commission announced that it would pursue the case through the European Court of Justice. [C R D]

While this disagreement between France and the Commission (as well as the UK) was developing, there was some concern that Germany would also maintain a ban on importing British beef. However, the German government insisted that any delay was due to a constitutional requirement to consult the constituent Länder (or states) that make up the Federal Republic before such a change of policy could be made. Indeed, the Bundesrat (the second chamber of the Federal Republic, in which the Länder are represented) voted in favour of lifting the ban in March 2000 and it was formally lifted later that month. [D]

It took until December 2001 for the European Court of Justice to rule that, by refusing to permit the marketing in its territory after 30 December 1999 of DBES beef which had been correctly marked or labelled (and which should have served to devolve decision making about risk to the consumer), France had failed to fulfil its obligations. During early 2002, the EC employed various devices to ask formally for an explanation of France's failure to comply with the European Court of Justice's ruling. This culminated in June 2002 in the Commission issuing a further Reasoned Opinion to the French government and giving it 15 days to respond. In July, the Commission requested that the Court impose a penalty of ?158 250 (about £110 000) per day on France for non-compliance with the Court ruling that its ban on the import of UK DBES beef was illegal. The French Food Standards Agency announced in September 2002 that British beef no longer posed a risk to French consumers and the French government formally lifted the ban the following month. In response, the EC announced in November that it was dropping the European Court of Justice case to impose financial penalties on France for illegally banning British beef. For the first time since March 1996, British beef could again be marketed throughout the EU and elsewhere. [C R D]

Question 57

What do you think motivated the French government to maintain its ban for so long? [C R D]

Answer

It could be argued that it was simply following independent science-based advice from its national Food Standards Agency. In other words, it was applying the precautionary principle. However, it is unlikely that the French government was unaware of the potential commercial advantages to France's own beef industry of continuing the ban for as long as possible. The battle between France and the EC (and, by implication, the UK) certainly engendered a great deal of adverse publicity for British beef. Of course, the eventual removal of the ban did not ensure that French consumers would actually buy British beef! (This is an example of decision making at a local level.) Ironically, in this instance more informative labelling of the origins of a product may have worked against the export of British beef to France.

On the other hand, the effects of BSE on British farming - and eventually on the health of some UK residents - were so severe that it is hardly surprising that a neighbouring country had serious reservations about allowing resumption of British beef imports.

In December 2004, the UK government announced that the 30+ months ban would be phased out over the succeeding months. [D]

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