Although STD can be transmitted in this way, it is NOT the only way.
I had tests for SYPHILIS, GHONEREA, AIDS, HEP a,b,c, plus lots of others last year for odd health problems, and this was for having blood transfusions in 1983, from a hit and run drink driver who put me in hosp for 19 months, first three in a coma.
Whilst waiting for results, I have never been so scared, really shit meself.
tabetha