Well now, if you didn't know before, you do now, trains have been bugged and de-bugged. How has this miracle come about?
The Guardian newspaper Bad Science editor, was attracted by the numbers of the train bugs that were meant to be in existence, so, he set about investigating the stories. A firm who unblock drains, kill bugs and so on, he discovered, simulated with a computer model, the perfect growing conditions for bugs to live in trains. You have to understand that there were no people on the modelled train, the train had a constant and stable temperature, not possible with an everyday train in use. The model 'grew' its bugs beautifully.
Somehow, the modelling exercise became 'common currency': trains carried thousands of bugs ripe for attaching themselves to passengers. It was wonderful stuff, and the name of the firm, which will remain anonymous in this post, got great free publicity in the media and alternative medias.
However the intrepid reporter had difficulty getting the truth of the matter out of the company, which, when it was uncovered, did no-one involved any favours. There appears to be rather too much storytelling, like the boy who cried "wolf"!