Volume 5: Animal Health, 1989-96
2. The ruminant feed ban, 1989-96
The chronological account
Developments in 1991 - the first BAB is confirmed

Developments in 1991 - the first BAB is confirmed

The first BAB - maternal transmission is considered

2.99 On 22 March 1991, soon after Mr Meldrum expressed to the Lamming Committee his doubts over controls on BSE, ¹ Mr Taylor reported to Mr Gummer the first confirmed case of BSE in an animal born after the introduction of the ruminant feed ban (BAB). The infected animal was the progeny of a cow confirmed as having BSE in March 1989. Mr Taylor advised:

This is not the first confirmed case of BSE in the offspring of a confirmed dam: there have been 23 others, but they were all born before the introduction of the feed ban and so exposed in the same way as the other 25,000 confirmed cases.

Although this could be the first case of maternal transmission of BSE, further detailed investigations on the farm and at the feed suppliers have still to be carried out before the probable cause of infection can be established. These investigations are being carried out as a matter of urgency. ²

2.100 Mr Lowson provided Mr Gummer with a draft question for written answer and a news release on 25 March 1991 to announce the BAB's discovery in a 'low-key way'. In his covering minute, he noted:

Further detailed work needs to be done on this case, in particular to establish conclusively whether or not the animal might have been fed on ruminant-derived protein (e.g. as a result of using up old stock or accidentally being given feed from the poultry operation on the same site). ³

2.101 The news release was issued on 27 March 1991. It noted that:

The [BAB] was born in November 1988, after the imposition of the feed ban. This one animal should not have been fed on ruminant-derived protein and its feeding regime, and other possible sources of infection, are being investigated. ⁴

2.102 In a statement to the Inquiry, Dr Matthews explained that although the case was born to a mother that had died of BSE, MAFF also investigated whether or not the suspect had been fed compound feed manufactured before the feed ban, or feed for poultry housed on the same farm. As indicated in following paragraphs, 'at that time it was concluded that feed sources had been eliminated as potential sources'. ⁵

Problems with the ELISA test emerge

2.103 During his attendance at the Lamming Committee meeting on 13 March 1991 (see paragraphs 2.144-2.145), Mr Meldrum undertook to provide a detailed paper on the ELISA test. On the next day Mr Lowson sought information on the test from Dr Cawthorne. ⁶

2.104 Dr Cawthorne replied on 9 April 1991, and outlined the current position:

We now have an ELISA test which has been validated and which can detect bovine protein at a concentration of 1/400 and ovine protein at a concentration of 1/200 in samples of meat and bonemeal which have been heated to temperatures greater than 130ºC.

Work is in progress to determine whether the same test can be used to detect ruminant protein in samples of finished/compound feed. The results of this validation should be available towards the end of this week. ⁷

2.105 On 11 April 1991 Mr Ansfield explained to Mr Hunter the difficulties he was having with using the ELISA test on compound feeds. In particular:

One of the major problems I have found with compounded feeds in relation to the ELISA test is that the majority produce positive results even without the inclusion of known positive meat and bone meal . . . As yet more work has to be done in this area . . . ⁸

SEAC considers the first BAB

2.106 SEAC discussed the first BAB at its meeting on 10 May 1991. SEAC had been provided with background information on the BAB in a minute from Mr Bradley. It recorded that there was no pig food kept on the farm where the case was discovered and poultry food was kept in hoppers inaccessible to cattle. Cattle feed was received in bulk into one-ton bags. It also noted that the SVS was investigating what care was taken with residual food in bags before refilling. ⁹ The minutes of the meeting note:

. . . that the possibility that the animal concerned had been fed on ruminant protein could not be fully ruled out. But even if it could, this case, and further similar sporadic cases at a low level in the future, would not alter the Committee's view of the disease and the advice that had been offered. There were apparently no similar cases in the field and no positive results had occurred in the offspring study, whereas if BSE were going to be widely transmissable more examples would have occurred. ¹⁰

2.107 At its meeting on 28 June, it was reported to SEAC that, following epidemiological investigations, a food source for the single confirmed BAB case could now almost certainly be ruled out. ¹¹

Investigations into the cause of BABs continue

2.108 On 12 June 1991 Dr Matthews reported the results of further investigations into the BAB case to Mr Meldrum. On feed, Dr Matthews stated:

Investigations . . . have included detail of feed supplies, the potential for carry-over of feed from before July 1988, and for the use of poultry feed intended for the intensive poultry unit on the same premises. Details of feed composition have been received from suppliers after some delay. All feed sources have been eliminated as potential routes of transmission. ¹²

2.109 Dr Matthews concluded that the most likely route of infection for the BAB was maternal. ¹³

2.110 Mr Meldrum responded to Dr Matthews on 18 June 1991, stating:

I would be grateful if you could re-examine the composition of the feed fed to the animal and let me have full details including as to whether any animal fat was ever fed to the animal either as a calf or cow. ¹⁴

2.111 Dr Matthews provided 'a limited amount of additional information' on 4 July 1991. He reported that two concentrate feeds were given to the BAB in its first year of life, with one company 'insisting' that the feed it provided contained no raw material of animal origin. It was proving more difficult to obtain details of the other feed provided by a different company, though it was likely that it contained fats of animal origin. Dr Matthews had asked the local VO to pursue this matter further. ¹⁵

2.112 Dr Matthews minuted Mr Meldrum again on 16 July 1991 with further details of the fat included in the second concentrate feed. He set out the percentage breakdowns in the feed, which included 10 per cent residues of soyabean and tallow. Mr Meldrum advised Mr Lowson and Mr Lawrence two days later in a manuscript note on the minute, that the inclusion rate of the tallow in animal feed was extremely low and that he thought it was 'highly unlikely' that it caused BSE in the BAB. ¹⁶

2.113 On 17 July 1991 Dr Matthews reported to Mr Ian Robertson, ¹⁷Mr Wilesmith, Mr Taylor and Mr John Maslin ¹⁸ that 26 suspected cases of BABs had been listed by the SVS. Two of those were recorded as positive at the CVL, but Dr Matthews awaited confirmation of the dates of birth. Three of the suspect cases had been born more than four months after the ban. The SVS continued to consider the possibility of maternal or horizontal transmission in these cases. ¹⁹

2.114 Mr Wilesmith wrote to Mr Hayward, DVO Carlisle, on 29 July 1991 about the second case of BSE in an animal born after the ban. Mr Wilesmith noted that 'this animal appears to have an accurate date of birth and was born very soon after the ban'. However, further details were needed:

The main aspect of interest is whether there was any accidental feeding of concentrates containing meat and bone meal. The feeding history of the animal probably needs confirmation as the BSE1 gives a history from 1986. Then, in the first instance determine the herd owner's feedstuffs purchasing regime in terms of the frequency of supply and the turnover of food stocks on the farm. If it appears that there was no accidental feeding then we will need to direct enquiries to the feed compounders . . . ²⁰

2.115 The second BAB was confirmed on 16 September 1991 and reported to Mr Meldrum by Dr Matthews. The second confirmed BAB was not the offspring of a confirmed case. Dr Matthews said:

While horizontal transmission and feed still have to be eliminated as possible sources, I am sure that vertical transmission would be the easiest to handle politically, given that the VO is certain that there will have been no carryover of feed containing meat and bone meal. ²¹

2.116 Dr Matthews attached a 'summary of the current state of play'. The probable origin of infection for the first case was recorded as 'maternal'. Two other previously reported BABs were also noted, though both had since been disregarded. The first was discounted because its calving date was not precise and carry-over of feed was likely. The other's date of birth could not be confirmed. ²²

ELISA test progress

2.117 On 16 September 1991 Mr Ansfield reported progress on the ELISA test to Mr Hunter. The problems with using the test on compound feeds had not been resolved, but for 13 out of 27 compounded feeds, bovine and ovine meat and bone meal residue could be detected down to 1 per cent. For the others, non-specific results were still being obtained. ²³

2.118 Dr Cawthorne relayed this information to Mr Meldrum on 19 September 1991. He attached a draft letter for Professor Eric Lamming, as promised by Mr Meldrum when he appeared before the Lamming Committee in March (see paragraphs 2.144-2.145). ²⁴ The letter was sent on 23 September 1991 and stated:

We now have a validated ELISA test which can detect bovine protein at a concentration of 1/400 and ovine protein at a concentration of 1/200 in meat and bone meal derived from material heated to temperatures greater than 130°C.

Unfortunately, problems were encountered when the test was applied to compound feedingstuffs and we have had to develop methods to overcome them. Progress has been made and I am pleased to report that we can now detect bovine and ovine proteins in a sizeable number of compound feedingstuffs at incorporation rates as low as one per cent. Work is continuing and I will keep you informed of developments. ²⁵

The Bovine Spongiform Encephalopathy Order 1991

2.119 The Bovine Spongiform Encephalopathy Order 1991 (the Order) came into force on 6 November 1991 (see Chapter 4). ²⁶ The Order consolidated the Bovine Spongiform Encephalopathy (No. 2) Order 1988 and the 1990 BSE Amendment Order. Article 12 of the Order provided:

(1) . . . no person shall -

(a) knowingly sell or supply for feeding to ruminant animals any feedingstuff in which he knows or has reason to suspect any protein which is derived from a ruminant animal has been incorporated;

(b) feed to a ruminant animal any feedingstuff in which he knows or has reason to suspect that any protein which is derived from a ruminant animal has been incorporated . . .

2.120 Article 15 stated:

Where an inspector of the Minister has reasonable grounds for supposing that the provisions of article . . . 12 . . . have not been or are not being complied with he may take from any protein, offal or feedingstuff such samples as he considers necessary in order to establish the correctness of that supposition.

2.121 This removed the anomaly in the Bovine Spongiform Encephalopathy (No. 2) Amendment Order 1990, whereby a ban was placed on the feeding of all animal protein to ruminants (see paragraph 2.85).

The number of BAB cases increases

2.122 By 15 November 1991, five BAB cases had been confirmed, with another four likely to be confirmed. Dr Matthews informed Mr Meldrum that he was concerned at MAFF's inability to link four of those cases with food or an infected dam, which would 'raise the profile of horizontal transmission in the eyes of importing countries'. ²⁷

2.123 Mr Wilesmith raised further concerns when he wrote to Mr Meldrum on 21 November 1991:

As Danny Matthews' initial summary of the cases born after the [ban] indicates we have a number of problems with these cases. We have taken action to obtain as rapid a flow of information in a standard manner, but at any point in time we will always have incomplete information on a number of cases. Also, it is clear from the handful so far dealt with that not all relevant information will be available, especially to assess the risks of a food borne source.

. . . It is becoming increasingly difficult to provide a succinct summary of the state of play. I would be very grateful if we could discuss the presentation of information in order to have a standard agreed format and the details required for summaries of this set of cases for internal circulation. ²⁸

2.124 Following a request from Mr Meldrum to deal with the matter, ²⁹ Mr Taylor wrote to all RVOs on 24 December 1991. He noted that the large number of referred BAB cases was stretching diagnostic resources at CVL to the limit. Further, out of 177 brains examined, only 10 had been confirmed with BSE. There were 39 results pending. He said:

To ease the burden for the laboratory staff who have to carry out detailed histopathological examinations and for those involved in obtaining epidemiological data in the field, it is essential that as many as possible of these negative cases are eliminated at the stage of clinical assessment on the farm. ³⁰

ELISA test progress

2.125 Meanwhile, Mr Ansfield had written to Mr Hunter on 10 December 1991 informing him that all 27 compound feeds tested gave a positive result when 1 per cent bovine meat and bone meal was added. However, the addition of ovine meat and bone meal did not give results, so work was to continue. ³¹

2.126 In a statement to the Inquiry Sir Derek Andrews, MAFF Permanent Secretary from 1987 to 1993, summarised his view of the developments during the latter half of 1991:

I was aware that there was a growing - but still small - number of BSE suspects born after the feed ban. It became increasingly likely that some cattle had in fact been fed with ruminant feed after the feed ban came into force. There was still no test in use to establish whether feed contained ruminant material. This meant that enforcement depended largely on visual inspection in feedmills and at farms. Given the number of separate premises at which feed might be stored, it was not surprising that there had been some enforcement problems. ³²