Any time a person engages in sex or sex-like activity with a partner, there is a chance of contracting a sexually transmitted disease (STD) or sexually transmitted infection (STI). You can contract an STD through oral, anal, or vaginal intercourse and genital touching. There are estimated to be 20 million new sexually transmitted diseases/infections each year in the United States alone. Even if a person looks perfectly healthy, they can still transmit an STI and not even know it because symptoms are not always obvious. Many STIs/STDs are curable if they are caught early. If left untreated, many can cause serious medical conditions. Testing regularly and early detection is extremely important.