Of course there are. The faecal matter (e.g. from egg shells, as described in the article) can be transferred onto hands, and from there onto clothing. The person then hops on a plane, flies to UK and goes for a stroll around British countryside, where they come into contact with some chickens.

This is contrived, admittedly, but not implausible. There are other scenarios as well. While they may all seem very unlikely, eventually contamination will occur, given how often people fly back and forth nowadays. If you keep rolling a thousand dice, eventually they will all come up sixes.