It's clear that having an untreated STI increases the risk of transmitting the infection to others. Even if you use condoms and practice safer sex, the risk of transmission remains significant. This is especially true for STIs, such as human papillomavirus (HPV), for which condoms only provide partial protection. Gonorrhea often has no symptoms, but it can cause serious health problems, even without symptoms.
If left untreated, syphilis can kill and gonorrhea can cause infertility. Non-viral STDs, such as chlamydia and gonorrhea, can be cured. However, they usually have no symptoms, or symptoms may come and go, making it look like an infection went away when it actually didn't. You can't know your STD status without getting tested, and you can't self-diagnose an STD based on symptoms and then assume that the infection is gone when your symptoms go away.
Getting tested can uncover a problem and pave the way for treatment. Men can get trichomoniasis, but they usually have no symptoms and are not tested for trichomoniasis as part of routine STI screening. Trichomoniasis is the most common curable sexually transmitted disease in the country, and it is estimated that it infects about 3.7 million Americans at a time, 70 percent of whom have no symptoms.