Sexually transmitted infections

What is an STI?

A sexually transmitted infection is transferred from one person to another through intimate physical contact, usually sexual.

A person can be infected with an STI and transmit it without being sick. Most STIs do not show clear signs when they are present, especially at the beginning stages of an infection. This is why infected persons can transmit their infection without being aware of it. An STI’s signs are often very subtle and intermittent. You do not have to have many partners to contract an STI.

How are STIs transmitted?

Condyloma, genital herpes and syphilis can be transmitted by direct contact, sexual or not, with an infected person. Crab louse and scabies are not considered STIs, but can be transmitted through direct contact, and simply through contact with contaminated sheets, clothes, or towels.

Gonorrhea, chlamydia, condyloma, hepatitis B, genital herpes, syphilis, and HIV can be transmitted through unprotected sexual relations, whether vaginal, anal or oral.

HIV, hepatitis B or C, and syphilis can be transmitted through a contaminated syringe.

Hepatitis A can be transmitted by oral-anal sexual relations with a person whose stools are infected.

How to protect oneself?

The possibility of contracting an infection increases with the number of unprotected sexual relationships. Prevention is the best way to protect yourself against an STI. Adopt safe sexual habits by always using a latex or synthetic condom.


The human papilloma virus, or HPV, causes STIs. Some types of HPVs are associated to a risk of developing cervical cancer. Often, the virus manifests itself through condyloma. Infection of the cervix by the HPV is detected via a cervical cytology. Most persons infected do not have any symptoms of the virus. Using a condom greatly reduces the risk of contracting the HPV, unless the lesions are on areas not covered by the condom.


Condyloma, or genital warts, are caused by the human papilloma virus (HPV), and are usually visually detectable in and around the vagina, the penis or anus, and can cause a cervical infection. There are several treatments for genital warts, but the virus can remain in the system even if the warts have disappeared, which means they can eventually reappear. 90% of affected people are cured definitively.

Genital herpes

This is an infection caused by the herpes simplex virus and is usually transmitted through unprotected sexual relations. Symptoms include urinary burning, lesions, pain in and around the genital organs, or fever and aches. Several antiviral treatments are available.


Chlamydia is a sexually transmitted infection caused by bacteria. Although it is often an asymptomatic infection, it can cause vaginal discharge, abnormal discharge from the penis, a burning sensation while urinating, or pain during sexual intercourse. In women, untreated chlamydia can progress towards the uterus and the fallopian tubes, possibly causing salpingitis and sterility. In men, the infection can lead to pain in the genital organs. Chlamydia is easily treatable with antibiotics.


Gonorrhea is a sexually transmitted infection caused by bacteria and is often asymptomatic, but in some cases it can cause abdominal pain, pain during sexual intercourse, abnormal vaginal bleeding, a burning sensation while urinating, abnormal discharge from the penis, and fever. In women, untreated gonorrhea can progress towards the uterus and the fallopian tubes, possibly causing salpingitis and sterility. In men, the infection can cause pain in the genital organs and lead to serious damage. Gonorrhea is treatable with antibiotics.


Trichomoniasis is a sexually transmitted infection caused by a parasite that produces infections in and around the genital organs. In women, these infections can cause a vulvovaginitis with abundant discharge, itching, and pain during sexual intercourse. In men, the parasite can cause a urethritis or a balanitis.


Syphilis is a sexually transmitted infection spread through the blood (skin lesions) and mucous membrane. The primary stage is characterised by the appearance of lesions, usually on the genital organs. The secondary stage is characterised by the appearance of lesions on the skin elsewhere on the body and mucous membranes, and is often accompanied by fever. The tertiary stage occurs when the infection has not been treated. Syphilis is treated with antibiotics.


Hepatitis refers to any inflammation of the liver, among which the most common are the viral forms. Hepatitis B is extremely infectious and is transmitted through sexual intercourse or contact with infected blood or other organic fluids. It attacks the liver directly, provoking a serious illness and hepatic lesions. A safe and effective vaccine is used to prevent the disease.

Hepatitis C is transmitted almost exclusively through the blood.


The human immunodeficiency virus (HIV) is the virus that leads to acquired immunodeficiency syndrome (AIDS) and can be transmitted via the blood, the sperm, the pre-ejaculate fluid, vaginal fluids, and breast milk. Transmission can happen during unprotected sexual relations, the sharing of unsterilized syringes, a pregnancy, or when giving birth or giving milk to a child (when the mother is HIV positive). The virus weakens the immune system until it can no longer fight the infection.

Some HIV-infected persons do not develop the symptoms. Available treatments increase life expectancy and improve the quality of life of infected persons, but there is yet no treatment or vaccine that prevents the infection or cures it.

Crab louse

Crab louse, also known as the pubic louse, is a parasite that, when seen through a microscope, looks like a brown organism with crab-like claws. The crab louse is usually transmitted by sexual contact with an infected person, but direct or indirect contact with contaminated objects like clothes, sheets, toiletry, and towels. It is found on the hair in the pubic area, the armpits and the anus, and in beards, eyebrows and lashes.

Symptoms usually revolve around itching in the hairy areas of the body and can take several days and even weeks before they appear. The infection is treated with lotions, creams or shampoos.


Scabies is a skin disease caused by a parasite that feeds on the surface layer of the skin, creating a scab. It spreads quickly, usually through sexual contact and direct or indirect contact with an infected person.

Symptoms include intense itching all over the body, especially at night. Scabies is diagnosed by the presence of lesions. The infection is treated with lotions, creams or shampoos.

Vaginal infection

Vaginal infections, most often associated with vaginitis (inflammation of the vagina), include yeast infections, bacterial vaginosis, trichomonas vaginitis and contact or allergic (chemical) dermatitis. Several factors can contribute to the development of vaginal infections, such as the use of vaginal douches and perfumed soaps, the use of antibiotics, wearing clothes that are too tight, the use of sanitary napkins, pregnancy or diabetes.

Symptoms can include redness, itching, a burning sensation, discharges, abnormal odours, vulvovaginal pain and stomach cramps. The infection is diagnosed with an examination of vaginal secretions with a microscope, as well as other lab tests.

Available treatments include vaginal creams, antibiotic tablets and antifungal suppositories. Some are over-the-counter products.


Salpingitis is an infection that affects the fallopian tubes. It is one of the main causes of sterility in women. Infection of the fallopian tubes is usually caused by a sexually transmitted infection like chlamydia and gonococcus.

Symptoms can include abdominal pain, excessive bleeding, nausea and fever, or vaginal discharge. Salpingitis can also be asymptomatic.

Salpingitis can be diagnosed during a routine gynaecological examination. It is treated with oral antibiotics. In more severe cases, treatment can require hospitalization and intravenous antibiotic therapy.


Prostatitis is an inflammation of the prostate gland (which secretes ejaculatory fluid) generally caused by bacteria. It is not a transmittable infection. The risk of developing prostatitis increases with age. Approximately one man in ten is affected by prostatitis. Symptoms include various urinary disorders, pain in the area between the scrotum and anus, or ejaculation problems. Antibiotics are used to treat these bacteria.

For more information, please visit: the Health Canada website

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Contact us

  • Address: Clinique Médicale de l'Alternative
    2034, Rue St-Hubert
    Montréal, Québec
  • STI and Gynecology: (514) 281-9848
    Abortion: (514) 281-6476
  • Monday to Thursday: 8:30AM to 5:00PM
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