Dear Counselor, can a person have a Sexually Transmitted Infection (STI) and not know it?

Yes.  Some Sexually Transmitted Infections (STIs) do not present any signs and symptoms especially among women. Chlamydia is one of the most common treatable STIs but about three-quarters of the women and about half of the men with Chlamydia have no STI symptoms. Many other STIs can also lie dormant for months or even years without showing any symptoms.
STIs which show no signs or symptoms are called asymptomatic STIs. It is very easy to have an STI and not know about it and you can easily pass it to other people without even knowing it.
Although a Sexually Transmitted Infection (STI) may not be making you feel sick right now, it does not mean that it is not having an effect on your or your sexual partner’s health. Left untreated, some STIs can cause long-term damage to the reproductive tract such as pelvic inflammatory disease and make it difficult or impossible to have children.