Consequences, Risk Factors & Prevention of STIs


  • The high incidence of chlamydia has become a global public health concern. Each year, there are nearly 100 million new cases of chlamydia worldwide.
  • Studies show that having an STI such as chlamydia increases the transmission and acquisition of HIV infection.
  • Approximately 70% of females and 50% of males infected with chlamydia, do not have any symptoms. As a result, chlamydia is under-diagnosed.
  • In women, untreated STI such as gonorrhea and chlamydia, can lead to pelvic inflammatory disease (PID), which is an inflammation of the internal female reproductive organs. PID may lead to chronic pelvic pain, ectopic pregnancy, or infertility. About 75-85% of PID cases are a result of chlamydia or gonorrhea infections that have spread to the reproductive organs.
  • Untreated STIs such as gonorrhea and chlamydia can put young men at risk of testicular infections and in rare cases infertility.
  • STIs such as gonorrhea and chlamydia can be passed from mother to child during birth causing eye infections, blindness, and pneumonia.
  • HPV is probably the most common STI in Canada. It is estimated that roughly 70% of adults will have at least one type of HPV infection during their lifetime. Many people infected with HPV have no symptoms.
  • There are over 140 strains of HPV. Certain strains cause genital warts whereas others cause abnormal cell growth on the cervix, which may lead to cervical cancer if left untreated.

Risk Factors

Several factors place an individual at risk for contracting STIs and/or HIV including:

  • Participation in unprotected vaginal, oral or anal sex (no condom or dental dam used)
  • Genital to genital sexual contact
  • Involvement in street culture
  • Previous history of STIs
  • Having multiple sexual partners
  • Use of non-barrier contraceptives, such as the birth control pill, without using a male or female condom
  • Use of injection drugs, alcohol or other substances that can impair decision making ability


  • Teens should be encouraged to consider or re-consider abstinence. When trying to avoid STIs, abstinence means avoiding vaginal, anal, oral intercourse and other behaviors (e.g., genital to genital contact) that expose a person to semen, pre-ejaculate fluid, cervical or vaginal secretions, and blood.
  • Male and female condoms reduce the risk of STIs like chlamydia, gonorrhea, syphilis, HPV, and HIV
  • Dental dams are square pieces of latex, similar to the material condoms are made from. They are used to cover the vulva or anus during oral sex to lower the risk of STI.
  • It is recommended that teens use a male or female condom and/or dental dam every time they have sexual contact (e.g., vaginal, anal, or oral sex; and genital to genital contact). The most common causes of condom failure are that they are not used consistently (e.g. with every act of intercourse) or correctly. Misuse of condoms account for condom breakage or slippage.
  • Teens should limit sexual activity to a partner they are sure has tested negative for STIs and HIV.
  • Health Canada has approved the use of two vaccines (Gardasil and Cervarix) to protect against different strains of HPV. The vaccine is approved for use in females and males aged 9-26.


Excerpt from: Sexual & Reproductive Health – Alberta Health Services Calgary Zone. (2013). TEENS AND TRENDS: Get the Facts on Teen Sexuality. Calgary: Author.