An STI is a sexually transmitted infection: an infection you can often get through sexual contact. STIs are also sometimes called STDs (sexually transmitted diseases) or VDs (venereal diseases).
Most STIs are curable. Most that aren’t curable are treatable, meaning that taking drugs can limit their symptoms and reduce the risk of passing them to someone else.
Why is it called an STI?
Sexually transmitted infections get their name because they often spread through sexual contact. They used to be called sexually transmitted diseases, but the term was updated to be more accurate. This is because infections don’t always cause symptoms or diseases. Someone with an STI might not show any symptoms at all. Also, not all infection become diseases.
For example, someone with HPV (human papillomavirus) has an infection. HPV can cause cervical cancer, but not always. So if their HPV doesn’t cause cervical cancer, they don’t have a disease. Some people living with life-long STIs, like HIV, also feel that the word “disease” is stigmatizing.
Some people also use the term STBBI, or sexually transmitted and blood-borne infections. The “blood-borne” part shows that someone doesn’t have to get the infection sexually. For example, someone can get HIV through sex. But they can also get HIV by sharing needles with someone who has HIV, without having sexual contact.
What kinds of STIs are there?
There are three main types of STIs: bacterial, viral, and parasitic.
Bacterial STIs are caused by bacteria, which are tiny living cells we can only see with a microscope. All bacterial STIs can be cured if the person finds out early enough. However, they can lead to serious health problems if they’re not treated in time. Some examples of bacterial STIs are:
Viral STIs are caused by viruses, which are tiny structures that reproduce inside living cells (like cells inside the human body). Viral STIs have no cure, but some people’s bodies can fight off some viruses on their own. Many viral STIs have treatments that will limit symptoms and reduce the risk of passing the STI. Some examples of viral STIs are:
- Hepatitis B
- HPV (human papillomavirus)
Parasitic STIs are caused by small insects or other living things. All of them have cures. Some common ones are:
- Pubic lice (also called crabs)
How do people get STIs?
Different STIs can spread in different ways. They commonly spread through sexual contact like oral, vaginal, or anal sex. For STIs that cause sores or warts (like herpes), touching the sores or warts with your genitals or mouth can also lead to getting the STI. For parasitic STIs, transmission is also possible if you touch the skin, pubic hair, towels, underwear, or clothing of someone who has the STI.
HIV and hepatitis B spread through five main body fluids of someone carrying the virus: blood, semen, vaginal fluid, breast milk, and rectal fluid (inside the anus). Transmission happens when one of the fluids carrying the virus gets into an entry point on someone else’s body. Entry points include the vagina, penis, anus, cuts or wounds, and being pierced by needles. This means that HIV and Hep B can spread through sex, but also through other things like sharing needles or giving birth.
Can I get an STI if my sex partner doesn’t have one?
STIs never create themselves. It’s important to remember that sex by itself doesn’t spontaneously lead to STIs. STIs only spread if people who are already carrying STIs have unprotected sex. If your partner doesn’t have an STI, they can’t give you anything.
However, many people who have an STI don’t know they do, because STIs don’t always show symptoms. If you want to protect yourself against infections, it’s a good idea to use protection, like dental dams or condoms, and get STI testing regularly. Head and Hands, a Montreal clinic for youth age 12-25, can be a great place for testing.
For more info on STIs, safer sex, and testing, check out the links below:
Basics of each STBBI — Heart your Parts
Heart your Parts compiles a list of STBBIs (Sexual Transmitted and Bloof-Borne Infections), with a quick description of each STBBI, whether it is curable and/or treatable, and what any treatment may be.
Possible STBBI symptoms – Heart your parts
This page lists possible symptoms for STBBIs (previously known as STIs or STDs). It also talks about the which STBBIs are treatable and which are curable.
Can I get an STI if…? – Options for Sexual Health
The Options for Sexual Health website answers common questions on scenarios and activities that put people at risk of STI transmission.
Assessing STI Risk — Heart your Parts
Heart your parts compiles a list of STBBIs (sexually-transmitted and blood-brone infections), and the transmission risk levels depending on sexual activity.
Testing, Testing – Scarleteen
A detailed look at the methods used for testing different STIs and BBIs.
How Long Should I Wait for STI Testing?
A look at the different types of STI testing, how they work and the importance of talking about it with your sexual partner.
Safe, Sound & Sexy: A Safer Sex How-To – Scarleteen
Ways you can reduce your risk of contracting STIs (such as barrier methods), information about testing, and other possible lifestyle choices.