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 sexually transmitted infections (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 Canada, chlamydia is the most common STI.
- Gonorrhea is an infection by the bacteria Neisseria gonorrhea. It is the second-most common STI, 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. It is also a very common STI in Canada, especially among teens and young adults. Research shows that the virus that causes genital warts is also linked to cervical cancer, as well as certain other cancers including cancer of the anus, penis, vulva, vagina and the back of the throat.
- Syphilis is a bacterial infection that is less common but still remains a cause for concern. Its frequency has dropped significantly over several few decades until the late 1990s, after which the rate has been steadily increasing in Canada.
- 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 defenceless 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 has become more frequent in recent years. It can cause genital ulcers.
- Pubic lice, also known as "crabs," is an infestation of the genital area by lice (tiny wingless insects).
- Trichomoniasis is an infection caused by Trichomoniasis vaginalis, a protozoan that affects women more often than men, and is often asymptomatic. This infection commonly appears along with gonorrhea and other STIs.