STIs: Who Is At Risk?

What Is an STI? 

A sexually transmitted infection or STI, is an infection passed from one person to another person through sexual contact. An infection is when a bacteria, virus, or parasite enters and grows in or on a person's body. STIs are also called sexually transmitted diseases, or STDs. Sexually transmitted infections affect millions of people every year,  both through previously established infections and newly acquired transmissions that originate from engaging in risky sexual behavior. While STIs can be an uncomfortable topic to discuss with a sexual partner, it should be a high priority because STIs are a prevalent concern in many people’s lives.  Additionally, many STIs, especially those that affect women, present asymptomatically (with no signs or symptoms.) Because of this, it can be difficult to know with certainty whether or not a partner is STI-free, since they might feel and appear alright.


Types of STIs

Of the eight most common STIs, four are bacterial, which means that current technology has provided us with the resources to cure the following infections: chlamydia, gonorrhea, syphilis, and trichomoniasis. The other four infections are viral and, therefore, incurable: hepatitis B, herpes, HIV, and HPV (human papillomavirus). Statistically, more than 1 million sexually transmitted infections are acquired every day world wide, while each year it is estimated there are about 357 million new infections involving 1 of the 4 bacterial STIs.3 STIs are predominantly spread through different types of sexual contact, including penetrative vaginal, anal, and oral sex. Some STIs can also be spread via non-sexual routes, such as blood or blood products.


Who Is Affected?

Currently, the CDC estimates that while anyone can contract an STI, certain groups like young people as well as gay and bisexual men are at the greatest risk.2 Young people between the ages of 15-24 account for about half of all new STIs, even though they only make up  25% of the sexually experienced population. Young females are at a particular risk because of the serious long-term health consequences that an STI may have.3 For example, chlamydia left untreated in females can result in PID, or pelvic inflammatory disease, which can lead to infertility (the inability to bear a child.) Another example is the direct correlation that has been drawn between STIs and other illnesses; there are estimates of nearly 528,000 cases of cervical cancer caused by HPV per year. While females usually deal with the most severe long term effects of STIs, both males and females are at risk.  For example, both sexes increase their chance of contracting HIV by nearly three times, simply by having an untreated case of herpes or syphilis.2

Other factors that increase the risk of contracting an STI include having sex with multiple partners and engaging in unprotected sex. The risk of acquiring an infection increases with the number of partners that a person interacts with. This is because there is a risk of being exposed to both the current partner’s possible infections and all their previous partners’ infections as well. 


Prevention Methods

There are a multitude of ways to avoid sexual transmission of STIs; the three most effective ways are 1) abstinence, 2) a long term, mutually monogamous relationship with someone who does not have an STI, and 3) correct and consistent usage of barrier methods of birth control, such as male and female condoms.1 If a person chooses to be sexually active, both they and their partner should undergo STI tests beforehand, and consider various protective contraception methods. It is important to note that most birth control does NOT protect against STIs, even if it does prevent pregnancy. 

This includes hormonal birth control (e.g., the Pill, Depo-Provera, NuvaRing, Implanon, and Nexplanon), and other forms of pregnancy prevention like spermicide. Because hormonal birth control does not protect against STIs, male latex condoms are one of the most highly effective methods of preventing STI transmission because they serve as barriers to STIs passed through genital secretions. Condoms are also relatively inexpensive and accessible. Other options include dental dams, which protect from STIs during oral sex, and female condoms, which may give females some shared responsibility and added peace of mind during sexual activity.1 The best way to be safe during sexual interactions is to communicate with a partner and discuss the importance of getting tested, using protection, and practicing safe sex. Approaching this subject beforehand can ensure a partner’s comfort and safety in this situation. Remember, “safe sex is great sex,” so taking the necessary precautions to protect each sexually active partner will result in a better, more pleasurable experience.



  1. "ReCAPP: Statistics: Sexually Transmitted Infections (STIs)." Resource Center for Adolescent Pregnancy Prevention,. Accessed 11 Oct. 2016.
  2. "Sexually Transmitted Infections (STIs) |" Office on Women's Health |, Accessed 11 Oct. 2016.
  3. "WHO | Sexually Transmitted Infections (STIs)." World Health Organization, Accessed 11 Oct. 2016.

Last Updated: 29 November 2016.