Biology

Sexually Transmitted infections

Big Picture

Sexually transmitted infections (STIs) are diseases that spread through sexual contact. Bacterial STIs can be cured with antibiotics, but viral STIs cannot. Since some STIs have little or no symptoms, they often go untreated and can lead to serious consequences such as cancer and death. The only way to prevent STIs is to avoid sexual contact.

Key Terms

Sexually Transmitted Infection (STI): Infection caused by a pathogen spread mainly through sexual contact.

Chlamydia: Sexually transmitted bacterial infection. Symptoms can include burning sensation, but oftentimes there are no symptoms.

Gonorrhea: Sexually transmitted bacterial infection. Symptoms can include painful urination, but may not always exhibit symptoms.

Syphilis: Sexually transmitted bacterial infection. Symptoms can include small, painless sores that go away after a while; if untreated, it can lead to death.

Genital Herpes: Sexually transmitted viral infection. Symptoms can include painful genital blisters that show up and go away and will occur periodically throughout life.

Hepatitis B: Sexually transmitted viral infection. Symptoms can include liver infection.

Human Papillomavirus (HPV): Sexually transmitted viral infection. Symptoms can include small, rough growths (genital warts) on the genitals; can cause cervical cancer in females.

Understanding STIs

To distinguish sexually transmitted infections (STIs) from other infections, the infection must have a small chance of spreading in ways other than sexual contact

  • The common cold can be spread by many means other than sexual contact, so the common cold is not a STI
  • Most STIs are caused by bacteria or viruses
  • Most pathogens that cause STIs enter the body through mucous membranes of reproductive organs
  • STIs are often transmitted through body fluids such as blood, semen, and breast milk
  • The sharing of infected needles is another way to spread STIs
  • STIs are common in young people
  • The only way to prevent STIs is to avoid sexual contact and risky behavior

Bacterial STIs

  • Bacterial STIs can be cured by antibiotics
  • Bacterial STIs often exhibit minor symptoms that can go unnoticed and thus untreated
  • If untreated, bacterial STIs can cause serious damage to the body
  • Most common bacterial STIs are chlamydia, gonorrhea, and syphilis
  • Chlamydia is the most common STI in the United States

Viral STIs

  • Viral STIs can’t be cured–once infected, will likely remain infected for life
  • Common viral STIs are: genital herpes, hepatitis B, and human papillomavirus (HPV)
  • The immune system usually is able to eliminate the hepatitis B virus, but the virus remains in a small number of people and can cause liver cancer
  • A vaccine is available to prevent infection with HPV for females aged 11 to 26 years.

Notes