Drivers for emerging issues in animal and plant health

Richardson, Jane; Lockhart, Caryl; Pongolini, Stefano; Karesh, William B.; Baylis, Matthew; Goldberg, Tony; Slingenbergh, Jan; Gale, Paul; Venturini, Tommaso; Catchpole, Mike; de Balogh, Katinka; Pautasso, Marco; Broglia, Alessandro; Berthe, Franck; Schans, Jan; Poppy, Guy

Horizon scanning is the approach to predict the next pathogen to emerge in animals, plants and/or being a threat for public health, both in terms of its route(s) of transmission and its origins (i.e. country and source reservoir). The emergence of a pathogen generally involves a combination of events together with a change in key drivers, typically socio-economic, environmental, climatic and/or zoological factors. Central to horizon scanning, therefore, is the construction of 'complex scenarios'. In a novel approach developed at a European Science Foundation-funded workshop in 2010, complex scenarios in the form of 'spidergrams' were produced by randomly linking factors, which may directly or indirectly affect the emergence of pathogens. The focus of the exercise was on viruses. The factors were chosen from a database under eight header categories (as defined by the workshop participants). Many thousands of scenario chains can be produced by this method and most may be irrational. However, the approach enables the testing of combinations not previously considered but which would be tested in nature. While it may not be possible to develop quantitative risk assessments for each combination, the approach provides a discussion focus for scientists of different disciplines and may help address identification of 'unknown-knowns' and even 'unknown-unknowns'. A problem with relying on such complex webs of putative drivers for prediction and management is that slight variation in the initial conditions will result in substantial impacts on the outcome of simulations based on those webs of drivers. An additional problem may be that both researchers and policy-makers might not be aware of such an issue.