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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 aris
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8 Managing the BSE/vCJD episode up to May 1990

BSE was formally recognised as a new disease in November 1986. However, this information was kept under ‘embargo’ at first while an initial epidemiological study – involving the collection of data from 200 herds – was started. The Ministry of Agriculture, Fisheries and Food (MAFF) was officially informed about BSE by the Chief Veterinary Officer (CVO) in June 1987. By December 1987, those responsible for analysing the data from the initial epidemiological study had concluded that the
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7 Managing the BSE/vCJD episode: an overview

Having concentrated so far on the ‘science’ behind BSE and vCJD, we now turn our attention to how the episode was managed by scientists, politicians and other relevant decision makers. Not surprisingly, we shall find that the themes of communication, risk and ethical issues are inextricably linked to that of decision making (at local, national and international levels).

Over the years, the UK Government implemented a great many Orders and Regulations, amending several of these more
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4 The emergence of vCJD

We now turn our attention to vCJD.

Question

If vCJD really is ‘the human form of BSE’ (as it is often described), how is it likely to have crossed the species barrier from cattle to humans?


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3 The origin and spread of BSE

Question

In the light of the above discussion about prions, what is the most probable explanation for the spread of BSE among cattle?

Answer

The cattle presumabl
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2 The biology of prions

The increasing interest in kuru during the 1950s and 1960s had the effect of stimulating research into TSEs in humans and other animals.

Question

Summarise, in general terms, the possible causes of disease in animals.


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1.5 BSE and risks to human health: vCJD

Given this background, it is not surprising that the possibility that BSE in cattle might pose a health risk to humans was given serious consideration from a very early stage in the outbreak. Various precautionary measures intended to eradicate BSE in cattle and also to prevent any possibility of transmission of the disease to humans were introduced. We will discuss these in more detail later in the unit. At the same time, the public was repeatedly assured by both officials (e.g. the C
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1.1 Unit overview

BSE and vCJD are important in their own right, having had major impacts on the lives of many people. Some people have died of vCJD and their deaths will have profoundly affected those who knew them. Large numbers of cattle have died either directly or indirectly because of BSE and this has had enormous economic effects on the agriculture and food industries. As a result, many practices in these industries are profoundly different from those of two decades ago. Although fundamental research in
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Introduction

The Open University course S250 Science in context looks at a range of science-based topics of current or recent importance to public debates about science. It does this by examining the scientific facts and concepts that underpin such areas as genetic modification, medicinal plants and climate change, and in doing so aims to forefront a number of themes that we feel are of value in gaining greater insight into these types of controversies. At the points in the text where one or more o
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5.3 Heat production

5.2 Metabolism

5.1 Warm-blooded vs cold-blooded

This section is concerned with another key mammalian characteristic. LoM highlights some of the essential terms and ideas – such as the notion of warm-bloodedness – but for more thorough study, some technical background is needed.

Activity 3

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3 Reproduction in marsupials

The study of mammals requires you to deal with measurements, which we call numerical ‘data’, and you will get practice with compiling and analysing data if you work through all the units in this series. We assume only that you can add, subtract, multiply and divide. In this section, we ask you to use units
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1 Overview

As you work through this unit you will come across boxes, like the one below, which give you advice about the study skills that you will be developing as you progress through the unit. To avoid breaking up the flow of the text, they will usually appear at the start or end of the sections.

As well as the unit text, you will be using The Life of Mammals book (LoM) and related The Life of Mammals DVDs, as described in the introduction to this unit. Before you go any further,
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Introduction

Mammals come in a bewildering variety of shapes and sizes and yet all of the 4700 or so species have some characteristics in common. Indeed, it's the existence of these common features that justifies the inclusion of all such diverse types within the single taxonomic group (or class) called the Mammalia.

This is the first in a series of units about studying mammals. To get the most from these units, you will need access to a copy of The Life of Mammals (2002) by David Attenboroug
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Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions) and is used under licence.

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

Text

Figures
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1.5.2 Instantaneous acceleration

The procedure of Question 15 for determining the instantaneous velocity of the car can be carried out for a whole set of different times and the resulting values of vx can be plotted against t to form a graph. This has been done in Figure 28, which shows how the velocity varies with time. At time t = 0 s, the car has zero velocity because it starts from rest. At later times, the velocity is positive because the car moves in the direction of in
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1.4.6 The signed area under a constant velocity–time graph

There is a simple feature of uniform velocity–time graphs that will be particularly useful to know about when we come to consider non-uniform motion in the next section. It concerns the relationship between the velocity–time graph and the change in position over a given time interval. Consider the following problem. A vehicle travels at a velocity vx = 12 m s−1 for 4 s. By how much does its position change over that interval?

The answer, fro
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1.4.5 Velocity–time and speed–time graphs

Just as we may plot the position–time graph or the displacement–time graph of a particular motion, so we may plot a velocity–time graph for that motion. By convention, velocity is plotted on the vertical axis (since velocity is the dependent variable) and time (the independent variable) is plotted on the horizontal axis. In the special case of uniform motion, the velocity–time graph takes a particularly simple form – it is just a horizontal line, i.e. the gradient is zero. Ex
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1.4.2 Constant velocity and the gradient of the position–time graph

Two things you will almost certainly want to know about any particle undergoing uniform motion are ‘how fast is it travelling?’ and ‘in which direction is it moving?’ The physical quantity that provides both these items of information is the particle's velocity. This is defined as the rate of change of the particle's position with respect to time, and has a constant value for each case of uniform motion along a line.

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