Human viruses: discovery and emergence

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

Whichever of these two models is correct (perhaps both), there is a clear implication that the emergence of new human viruses is a long-standing and ongoing biological process. Whether this process will eventually slow down or stop (if the bulk of new virus species constitute extant diversity) or whether it will continue indefinitely (if a significant proportion of newly discovered virus species are newly evolved) remains unclear, although this makes little difference to immediate expectations. There is a hint, from the slower accumulation of new virus families found in humans, that virus diversity may be bounded, but that does not preclude there being a much larger number of virus species 'out there' than we are currently aware of. If anthropogenic drivers of this process are important then it is possible that we are in the midst of a period of particularly rapid virus emergence and, in any case, with the advent of new virus detection technologies, we are very likely to be entering a period of accelerated virus discovery. The unavoidable conclusion is that we must anticipate the emergence and/or discovery of more new human viruses in the coming years and decades. By no means all of these will pose a serious risk to public health but, if the recent past is a reliable guide to the immediate future, it is very likely that some will.