Human viruses: discovery and emergence

Woolhouse, Mark; Scott, Fiona; Hudson, Zoe; Howey, Richard; Chase-Topping, Margo

To make shorter term projections, the model was extrapolated to year 2020, calculating 95% posterior prediction intervals using 2 million model simulations, taking into account parameter uncertainty and model stochasticity. An upper limit for N was set at the 90% upper confidence interval. This gave a projected number of new virus species of 36 (95% CIs 20-57), corresponding to an average 2.4 species per year. This projection, of course, makes no allowance for any improvements in virus detection technology nor changes in discovery effort. (table 2) , though this list is almost certainly incomplete. Clearly (subject to recognition of these new viruses as distinct 'species' by the ICTV), the projection described in §2d looks likely to be met. Indeed, it would be unsurprising if it were exceeded, given the considerable recent interest in virus discovery and the advent of high throughput sequencing as a detection tool.