Since sexually transmitted infections (STIs, also known as sexually transmitted diseases, or STDs) are transmitted via direct physical intimacy in the vast majority of cases, lifestyle choices regarding physical intimacy play a large role in determining an individual’s risk for contracting an STI.
It is important to remember that these infections are incredibly prevalent in our society, with an estimated 20 million new STIs each year in the United States. STIs affect people of all races, socioeconomic status, gender and sexual preference, and more than half of these new infections are in young people ages 15 to 24.
STIs are primarily transmitted through direct skin-on-skin contact. STIs are not transmitted through casual contact, such as hugging, shaking hands or talking with someone. Public toilet seats do not pass STIs from one person to another — ever. STIs are not spread through the air on respiratory droplets, like the common cold or the flu.
Pubic lice (also known as “crabs”) is the one exception to this rule, because although most cases are spread during direct sexual contact, these tiny insects can cling to bed linens or clothing and then be passed to another person who is in contact with that material. This is why it is important to wear underwear when trying on clothing in stores, especially swimsuits.
Number of Partners
The risk of contracting an STI increases with increasing numbers of sexual partners. Lifestyle choices that include frequent hookups will therefore increase your risk of STIs, while choosing abstinence or longer-term mutually monogamous relationships significantly decrease your risk.
Choosing to use dental dams or condoms consistently and for all forms of genital intimacy (oral, vaginal and anal) will decrease your risk of contracting an STI.
Type of Intimacy
In both males and females, receptive anal intercourse carries the highest risk for contracting an STI (if your partner is infected), because the lining of the anus is thinner and more fragile than vaginal tissue, so anal penetration more easily causes microscopic trauma, or tears, which reduces the natural physical barriers against infection.
STIs can be passed through oral, anal or vaginal intercourse, so gender, sexual identity or sexual preferences are not definitive in and of themselves. As a group, however, MSM (men who have sex with men) do have higher rates of HIV and syphilis, while WSW (women who have sex with women) have the lowest overall rates of STI transmission. Note, however, that a quarter of new HIV infections are transmitted through heterosexual contact.
Drugs and Alcohol
Lifestyle choices that include excessive alcohol, marijuana or other drugs make people much more likely to take sexual risks that will lead to STIs. Injection drug use and shared needles can directly transmit blood-borne STIs, such as HIV and hepatitis B and C.
Sex workers obviously have high numbers of sexual partners, which increases their risk of STIs. Studies show that sex workers are often financially incentivized not to use condoms, which further increases rates of STIs in this population. While paying for sexual intimacy increases your STI risk, note that the vast majority of STIs occur in people who are not sex workers.
Be sure your personal health checkups include discussions about vaccines that can prevent STIs. The HPV vaccines (Gardasil and Cervarix) and the hepatitis B vaccine are now routinely given at birth, but note that many adults over the age of 35 have not been vaccinated.