Ho hum … another deadly disease

Science magazine today publishes a paper about mapping the geographical spread of diseases. ((No link, because they’re so inaccessible. But the paper is Large-Scale Spatial-Transmission Models of Infectious Diseases by Steven Riley, which should enable people to find it.)) The key point is that different diseases spread in different ways, and recognising that should make prevention more effective.

It would be possible to run an entire blog on the emergence of diseases. Going well beyond the World Health Organisation’s monitoring systems, and prompted by Larry Brilliant’s TED wish, INSTEDD — International Networked System for Total Early Disease Detection — is starting to move. There are systems for veterinary and food borne diseases, and presumably some for plants too, although they are surprisingly hard to find on the internets. ((Help me, please! I know there are groups devoted to monitoring plant diseases, but aside from the usual suspect, which seems more interested in sexy animal diseases than dull old phytopathology, I cannot find them, honest.)) I’d like to read such blogs, but my point here is somewhat different. In a nutshell, agricultural biodiversity is likely to be a source of the solutions, both genetic resistance and as a buffer against disease spread.

In recent months we’ve seen UG99 wheat rust, Asian soybean rust, banana Xanthomonas wilt, cassava brown streak virus and now tomato leaf curl virus hit the headlines. Others too. By the time they make front pages news, these diseases are inevitably accompanied by estimates of the costs they will impose, and these can run into billions of dollars a year. And yet solutions, when they arrive, often go unnoticed. To some extent that’s a function of ADD among news organizations, which have a great deal of difficulty in understanding the process of science and so have very little time for long-term projects. To some extent it is because the solutions themselves often cannot exactly pinpoint specific contributions. A resistant variety may get its characteristics from several parents, as a result of many independent breeding and research efforts. It can be hard to trumpet that as a breakthrough worth stopping the presses for. And such resistant varieties may also take time to prove themselves, which also works against excited news coverage. As for the use of agricultural biodiversity to fight disease, that scarcely gets a mention.

We’ve heard a lot too about the Arctic (Seed) Monkeys and their plans to bury humanity’s global heritage of agricultural biodiversity in the frozen rock of Svalbard, but far less about the basic problem, which is that genebanks and conservation in the wild are starved of committed funding. Everywhere, it seems, people want convincing of the economic value of conserving agricultural biodiversity. At some point, I believe, one has to accept that it will never be possible to specify, in advance, the value of any particular bit of biodiversity. One has to go further and say that the manifest benefits of biodiversity to agriculture in just this one realm of defending our food supply against disease, are so large that the costs, whatever they may be, are trivial by comparison.

If some of those plant diseases caused real pain to the people who control the purse strings, perhaps the value of conservation would become more obvious. For now, I can only hope that agricultural biodiversity coughs up the solutions without too much delay. And when it does, we’ll try to take note here.

p.s. Of course, perhaps the biggest reason to fear disease epidemics relates squarely to human activity — the squandering of antibiotic sensitivity and vastly accelerated travel — which come together gloriously in today’s unfolding saga of the TB patient who took off on the lam. But I mustn’t abuse my position here to wail about those