What you need to know about sexually transmitted infections

One of the most important things to know about sexually transmitted infections is that the use of safer sex practices greatly reduces the risk of getting and spreading them!

The term sexually transmitted infection (STI) refers to a varied group of infections that are transmitted from person to person through sexual contact. Another term used to refer to these infections is "sexually transmitted and blood-borne infections" (STBBI). This term also includes sharing blood (e.g. through sharing used needles) as a way of transmitting these infections (e.g. HIV/AIDS).

What causes sexually transmitted infections?

Several microorganisms are responsible for STIs. These include:

Bacteria: STIs caused by bacteria can be treated (cured) with antibiotics. However, a person who has been treated for a bacterial STI can become infected again if they come into contact with the bacteria again.
There are three main STIs caused by bacteria:

• Chlamydia
• Gonorrhea
• Syphilis

Viruses: There is no cure for STIs caused by a virus, with the exception of genital warts, which can be removed. However, you can be vaccinated for some viral STIs (e.g. genital warts, hepatitis B). There are medications that can help reduce the symptoms of some viral STIs (e.g. genital herpes), but they are not a cure.
There are four main STIs caused by viruses:

• Acquired Immune Deficiency Syndrome (AIDS), which is caused by the Human Immunodeficiency Virus (HIV)
• Genital warts, which is caused by the human papilloma virus (HPV)
• Hepatitis B
  
• Genital herpes

Parasites: There are three main STIs caused by parasites.

• Trichomoniasis
• Pubic lice
• Scabies

The signs and symptoms of a sexually transmitted infection

Often, an STI will have no noticeable symptoms. This is why it is always important to protect yourself. The signs and symptoms of a sexually transmitted infection are varied. They include:

• Discharge from urethra
• Abnormal discharge from vagina
• Itching in genital or anal area
• Burning on urination
• Lumps or growths in the genital or anal area
• Bleeding after sex or between periods
• Pain in the abdomen
• Pain in vulva or testicles
• Yellow tinge of skin or eyes

The Mayo Clinic has quick list of common STDs and their symptoms.

How do sexually transmitted infections spread?

STIs spread when the causing micro-organism (e.g. bacteria, virus, or parasite) passes from a person to another person. This can happen during sexual activity that involves the penis, vagina, anus or mouth. It can also happen with simple skin to skin contact in the case of genital warts or genital herpes. Bacteria and virus can also be transmitted from one person to the next through sharing needles or sharing other objects (e.g. sex toys).

What are risk factors associated with STIs?

The following STI risk factors are associated with increased incidence of STIs. 
Source: Canadian Guidelines on Sexually Transmitted Infections, Public Health Agency of Canada

• Sexual contact with person(s) with a known STI.
• Sexually active youth under 25 years of age.
• A new sexual partner or more than two sexual partners in the past year.
• Serially monogamous individuals who have one partner at present but who have had a series of one-partner relationships over time.
• No contraception or sole use of non-barrier methods of contraception (i.e., oral contraceptives, Depo Provera, intrauterine device).
• Injection drug use.
• Other substance use, such as alcohol or chemicals (pot, cocaine, ecstasy, crystal meth), especially if associated with having sex.
• Any individual who is engaging in unsafe sexual practices (i.e., unprotected sex, oral, genital or anal; sex with blood exchange, including sadomasochism; sharing sex toys).
• Sex workers and their clients.
• “Survival sex”: exchanging sex for money, drugs, shelter or food.
• Street involvement, homelessness.
• Anonymous sexual partnering (i.e., Internet, bathhouse, rave party).
• Victims of sexual assault/abuse.
• Previous STI.

What are the consequences of getting a sexually transmitted infection?

There are a wide range of consequences from getting an STI. Depending on the type of STI a person is infected with the consequences range from mild irritation, to sterility to death.

For more information

To learn more about sexually transmitted infections, consult Sex and U from the Society of Obstetricians and Gynaecologists of Canada.