On epidemiologists' standard assumption that every individual counts, vaccination programmes are intended to prevent epidemics by ensuring that each infected animal, on average, passes the disease on to less than one healthy animal.

ECONOMIST: How to protect Ethiopian wolves from rabies

And by exploiting the Internet to distribute the cures to computer diseases, such systems offer a promising way to prevent outbreaks from becoming epidemics.

ECONOMIST: A thousand ills require a thousand cures