If you test positive for an STD, it is recommended that your recent and current sexual partners are also tested. This recommendation applies even if you consistently use condoms and your partner is not experiencing any symptoms. Although correct condom use does reduce the risk of transmitting STDs, it does not eliminate the risk, and many STDs are asymptomatic, meaning that there are no obvious symptoms, yet they can still be transmitted to others.
In addition, if you are successfully treated for an STD, but your partner is not tested and treated, you are at risk of your partner passing the STD to you again. Recurrent infections are associated with an increased risk of serious health complications.