The Facts
Sexually transmitted infections (STIs) are a group of infections similar to one another only in that they can be acquired through sexual contact. STIs is a term now used in place of sexually transmitted diseases (STDs).
You don't necessarily have to have sex to get STIs, but sexual activity is the most common way for them to be spread. The infections are caused by different organisms and have a wide variety of symptoms.
Here are some of the most common STIs:
- Chlamydia occurs most often in teens and young adults, with females much more likely to get it than males. It is caused by the bacteria Chlamydia trachomatis. In the United States, chlamydia is the most common bacterial STI.
- Gonorrhea is an infection caused by the bacteria Neisseria gonorrhea. It is the second most common bacterial STI in the US, and teens and young adults represent almost half of all cases that are reported. If this condition is not treated, it may lead to infertility in both men and women.
- Human papillomavirus (HPV) causes genital warts. Genital HPV infection is the most common STI in the US. Almost half the reported infections are in teens and young adults. Research shows that the virus that causes genital warts is also linked to cervical cancer.
- Syphilis is a bacterial infection that is less common but still remains a cause for concern. Its frequency in the US dropped significantly over several decades until 2000, after which the rate has increased dramatically.
- Human immunodeficiency virus (HIV) is the viral infection that can cause AIDS (acquired immune deficiency syndrome). This virus attacks cells of the immune system, leaving a person defenseless against many other infections and their complications.
- Hepatitis B is caused by a virus that infects the liver. There is no cure for this condition, but a vaccine is available to protect you against the virus.
- Genital herpes, which produces cold-sore-type lesions, is also caused by a virus. Once the herpes virus enters your body, it is there for the rest of your life. Symptoms of the infection may occur without warning.
- Chancroid, a bacterial infection of the genitals, was once rare in North America, but it has become more frequent in recent years. It can cause genital ulcers.
- Pubic lice, also known as "crabs," are an infestation of the genital area by lice (tiny, wingless insects).