Study leader Dr Gkikas Magiorkinis, from Oxford University, said when people were infected with something such as flu it was very easy to work out where it had come from, because people knew they were infected within days.

BBC: Spread of hepatitis C pinpointed

Everybody talks about the convention speech and how good it was, but I always say, I had good material to work with. (Laughter.) It was very easy.

WHITEHOUSE: Remarks by the First Lady at a Campaign Event

It is very easy to become close to others, and therefore easy to have a affair, get divorced, or lose a very valuable part of your marriage because work and friends simply and slowy comes first.

FORBES: Readers Say