[Steve]

Steve asked the Naked Scientists:

My family love your show and feel lost on a Sunday evening if you're not there.

We were discussing the question on where does sexually transmitted diseases originate. They have to have come from somewhere, don't they? I'm not sure how we got on the subject, but it's got us thinking!

Keep up the great work.

What do you think?

[paul.fr]

Don't know the answer, but it's a good question.
To slightly expand. If two people with no sexually transmitted deseases have sex and a loving relationship...by what means does one of them become infected? Are they just dormant, waiting for time, oppertunity and means?