Not all STDs present symptoms. This leads individuals who have not had safe sex, to think they have no disease. Symptomless infections develop and create more complicated long term problems if not treated. Infertility is often a distinct possibility.
STD's may be contracted by a virgin who has sex for the first time with someone who is unknowingly carrying an infection. Social perceptions often leave people reluctant to get tested. It is wise to get checked regularly for improved peace of mind.
Chlamydia and gonorrhoea are the most common infections and are checked for with a urine test. Both are sometimes symptomless but may cause infertility if gone unchecked. Syphilis and HIV are two STD's that have a more profound impact upon on your health. A blood sample is required to asses if you have these.
Herpes is not a disease that is easily tested for without symptoms. If you do have herpes then it is impossible to remove. However, the infection tends to remain dormant, and only requires attention when an individual exhibits sores and dry itchy skin. Swabs are taken and analysed to test for this.