EPIDEMIOLOGY - MAKING THE RIGHT CONNECTIONS

Written by Professor Graham Medley, Department of Life Sciences

Previously the Knowledge Centre featured the introduction to The New Optimists, a collection of essays in which scientists view tomorrow's world and what it means for us. This week we are presenting Professor Graham Medley's contribution - 'Epidemiology - Making the Right Connections' - which examines how an increase in interdisciplinarity could deepen our understanding of the spread of infectious diseases.

Optimism implies three things: future, probability and judgement. I cannot be optimistic about the past since it has already happened. I can only be optimistic when I have the option of being pessimistic – I cannot be optimistic about things that I know will turn out well. Human perception determines what ‘turn out well’ means; the universe is not optimistic, it just does. Tigers will go extinct in the wild (no room for optimism there), but ecology, and human society, will keep going. It is also easier, I think, to be optimistic about things that I know nothing about, so I will stick to my subject.

I work in infectious disease epidemiology, and my approach is essentially ecological, treating the pathogen-host interaction as an ecologist treats a predator-prey interaction. I collect data to understand the dynamic interactions between (at least) two populations, use statistical models to develop and test hypotheses about the relationships and devise mathematical models to explore the potential dynamics and, ultimately, to predict the impact of interventions such as immunization and quarantine. I can make this approach sound like the solution to all infectious disease problems, and have done so pretty successfully in the past. During my career, infectious disease epidemiology has changed from an interesting scientific inquiry to almost engineering-like rigour of design and assessment of interventions.

Our mechanistic understanding of how things work will improve, and some of these explanations will coalesce: old knowledge will be destroyed by new theories.

How will the subject develop? I am sure that infectious disease will continue to plague humankind and the animals and plants that they care about for the rest of my career – as well as the careers of all my past, current and future students. It will be good for our careers, but does imply that disease will continue to exact its tolls. I know that the quality of data will increase, and that new methods will be developed to analyse the data: the biological understanding will get deeper. Old paradoxes and conundrums will be resolved, and new ones will appear. We can do things now that were impossible dreams when I started my research career (in 1983), and I expect that my students will have the same experience. Our mechanistic understanding of how things work will improve, and some of these explanations will coalesce: old knowledge will be destroyed by new theories.

I am pessimistic that reductionist science will continue to dominate infectious disease epidemiology. But optimistic that the interdisciplinarity that is emerging will have far-reaching consequences, and that our understanding will widen as well as deepen. Jan Smut’s vision of a holistic science is probably no closer now than it was a century ago, but there is a realisation that if scientific understanding is to change human actions for the better, then the science has to address the problems rather than just addressing the problems it can solve. And it is deciding what the problem is, so called ‘problem-framing’, that I am most excited about.

The twentieth century showed how bad things could be when human systems (economic, political etc) go wrong. We should be, and probably are, working with moderate success to ensure that some of the same things do not happen again. I hope (but not very confidently) that we do not have to learn similar lessons about ecology in the twenty-first century – that it can be really bad if we do not pay attention to the system-level interactions among people and between people and the environment. Increasingly, we have come to realise that social-ecological systems are what we should be studying to find out what problems require a solution – and how that solution can be implemented.

As I write, the UK is in the middle of the first wave of the H1N1 influenza epidemic that was first detected in Mexico. It has been named ‘swine flu’ by the media, though it has little to do with pigs. But as a result of this name, Egypt decided to intervene by slaughtering its pig population, and many countries banned the import of pig products. Had the media latched onto the name ‘Mexican flu’, then no doubt Mexico and Mexicans would have been blamed for a purely ecological process.

Humans organize themselves into collective action that shapes infectious disease patterns, and infectious diseases in turn then shapes society.

After a period of panic, the UK population seems to have settled for a more pragmatic view. It has even been said that it is better to get infected with H1N1 influenza now, rather than later, in case it mutates to become more pathogenic. There has also been talk of ‘influenza parties’, at which people can deliberately become infected. The disease has changed social interactions, and social interactions have changed the disease.

I am currently working on governance of livestock disease in a multidisciplinary grant funded by the Rural Economy and Land Use (RELU) programme. The programme was set up largely as a consequence of the foot and mouth disease (FMD) epidemic that resulted in over 6.5 million livestock being culled and cost billions of pounds. We are studying the interaction between epidemiology, politics, economics and law in determining the patterns of livestock disease, and how the disease, in turn, affects these dimensions and their interactions.

The programme is itself an indication of this process, since the resources spent have been as a consequence of this epidemic, and will have an effect on future epidemics, but not necessarily just FMD. A key idea of our project is that we are treating several diseases simultaneously, since interventions (and changes in human activity generally) will have an impact on all diseases, not just the target. For example, the ‘influenza parties’ will also result in increased transmission of everything else, just as stopping movement of cattle between farms during FMD will have had an impact on every other cattle disease.

Humans organize themselves into collective action that shapes infectious disease patterns, and infectious diseases in turn then shapes society. Understanding these processes better will enable us to define the problems more acutely, and we will be able to develop natural and social scientific approaches to address these real problems. This is what I am optimistic about – even if it does not produce any results, it is going to be very interesting.