Comment: STDs are diseases where the primary vector is sex

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In reply to comment: A urniary tract infection (see in situ)

STDs are diseases where the primary vector is sex

But sexual activity can spread other diseases that aren't classified as an STD (or venereal disease).

Sex can most definitely cause a UTI (in fact it causes 75-90% in women.) It doesn't matter if you are promiscuous or monogamous. Sex can lead to disease. It can also make you more immune to disease. It goes both ways.

http://en.wikipedia.org/wiki/Urinary_tract_infection