Volume 2: Science
7. Conclusions drawn from the scientific response to BSE
Animal disease surveillance

7.67 We now turn to consider lessons that may be learnt about animal disease surveillance. The BSE story demonstrates the importance of the speedy identification of the emergence of any new animal disease - particularly any disease that may have implications for human health.

7.68 We discuss in vol. 3: The Early Years, 1986-88 the system of passive animal disease surveillance in the UK at the time that BSE was first identified. Early warning of outbreaks of novel diseases still relies largely on passive surveillance, ie, it depends on the reporting of affected animals from the farm or slaughterhouse, by individual farmers or veterinary surgeons, to the Veterinary Laboratories Agency (VLA) regional laboratories (formerly the Veterinary Investigation Centres). This situation was recognised in a consultation document on the effectiveness of the active and passive surveillance systems published by MAFF earlier this year, which lists among the objects of veterinary surveillance:

To provide an early warning system for new animal diseases, infections or intoxications. ¹

7.69 The document observes of the task:

This is provided mainly through submissions from private veterinary surgeons to the VLA regional laboratories and follow-up investigations and 'intelligence' gathered through interaction with private veterinarians. It has been put to us that the animal health surveillance system picked up BSE at a very early stage in the epidemic and, furthermore, this would have not been the case were it not for the regional laboratories noticing a new syndrome in cattle and comparing notes. ²

7.70 The observations in relation to BSE are not entirely accurate. As we have explained in volume 3, we do not believe that the surveillance system picked up BSE at a very early stage of the epidemic. Recycling was already advanced before BSE was identified, and there is anecdotal evidence of cows in the early 1980s and possibly earlier suffering from symptoms similar to those of BSE. Nor was there encouragement for the regional laboratories to compare notes. Nonetheless the passive surveillance system did result in the identification of the emergence of BSE at a relatively early stage of the epidemic.

7.71 We discuss in volume 3 evidence about the ability of the passive surveillance system to detect cases of BSE. In our view one reason why BSE was not picked up at a very early stage by the system was the lack of incentive for farmers to refer an isolated case of an unrecognised disease in their herd for laboratory investigation. Indeed, there was a positive disincentive, namely the cost of a post-mortem examination.

7.72 Since the emergence of BSE, it appears that the efficacy of the passive surveillance system as a means of detecting new diseases has worsened. MAFF's consultation document records in an annex a significant decline in the number of samples submitted for analysis to the Veterinary Investigation Centres/regional laboratories between 1990 and 1998: ³

		1990	1998
	Cattle	2,838	1,415
	Sheep	3,838	2,267
	Pigs	2,108	795
	Birds	8,093	2,673

7.73 It also reports a reduction in number of regional laboratories from 19 to 14 in 1990, and an indication that these are effectively operating as 'sentinel centres' rather than representatively sampling the herds. ⁴ The document includes a lengthy section on the strengths and weaknesses of passive surveillance. This begins:

The system of passive surveillance has been described in terms of a 'pyramid of scrutiny'. Under this description, for a passive system of scrutiny to be successful, animals must be under vigilance sufficient to permit the identification of changes from the 'norm'. The first level of scrutiny is provided by the livestock producer, who may decide not to seek assistance. The second level is provided by the alert private practitioner or veterinary inspector, who may decide that laboratory diagnostic testing is unnecessary. These two levels apply a screening process, through their discretionary choices, that stops many disease occurrences from benefiting from a definitive diagnosis offered by the laboratory, which represents the third level of scrutiny. On a continuous basis, the resulting laboratory volume reflects, in major part, the industry's and veterinary practitioners' assessment of the cost:benefit ratio associated with specimen submission. ⁵

7.74 The consultation document questions 'whether the current arrangement is an adequate basis for meeting MAFF's risk management needs'. ⁶

7.75 We urge those whose task it is to answer this question not to lose sight of the importance of an effective early warning system for an outbreak of a disease such as BSE, and of the corresponding need to encourage referral of cases by individual farmers and veterinarians.

7.76 We recognise the cost implications of maintaining the current network of laboratories, let alone providing more diagnostic tests more cheaply or freely in order to encourage submissions. It is unlikely that even a free service would ensure the submission of 100 per cent of cases that with hindsight turned out to be informative or significant. What is important is that some systematic assessment is made of the costs and benefits of the different approaches, such as targets for representative submissions, facilitated by vouchers or discounts, or agreements with sentinel veterinary practices, or other options. Economic realities mean that some form of subsidy needs to be considered if the cost:benefit ratio is to be swung in favour of specimen submission.

7.77 The emergence of BSE might now act as a case study against which such options could be assessed, to see when, where and how each might have been able to identify the new disease and at what additional cost. This is not to suggest that new diseases will be like BSE; rather that BSE with its long incubation period, lack of ante-mortem test and low in-herd incidence presents a severe challenge to any surveillance system and thus might act as a benchmark for any extreme case likely to be faced, and the costs and benefits of different ways of dealing with it.