The term STD, now used interchangeably with STI for sexually transmitted infections, lumps together several different kinds of infections. Some infections, such as herpes, can be transmitted through kissing or other contact with an open sore on the skin. They may or may not be apparent. Chlamydia is usually invisible in women. Herpes may cause a blister on the lips, genital or anal areas, or it may be in an asymptomatic phase in which no blisters or sores are present.
Some types require microscopic examination of tissues or of sores.
Others require a blood test. If you are at risk through unprotected sexual contact with someone in whom an infection could be present, then do not rely on self-diagnosis. Go to a doctor or clinic for accurate testing. Antibiotics can be very effective against bacterial infections. For example, chlamydia and gonorrhea, infections that can be very dangerous, can be treated with a one-dose medication available at the time you test positive for it, Knowles said.