Common STIs
Approximately 20 different infections are known to be transmitted through sexual contact.
Here are descriptions of some common STIs.
Chlamydia
- Caused by the bacterium Chlamydia trachomatis
- Can be transmitted during vaginal, oral, or anal sexual contact with an infected partner
- Many infected individuals will not experience symptoms, but chlamydia can cause fever, abdominal pain, and unusual discharge from the penis or vagina.
- Can be treated with antibiotics
- If untreated, can cause pelvic inflammatory disease, which can lead to chronic pelvic pain and permanent damage to a woman's reproductive organs. This damage may lead to ectopic pregnancy (in which the fetus develops outside of the womb, a condition that can be life-threatening) and infertility.
- Can be transmitted to fetus during pregnancy or to infant during delivery, causing eye infections or pneumonia. Antibiotic ointment is usually applied to a baby's eyes after birth to treat undetected chlamydia.
- Because chlamydia and gonorrhea often occur together, people who have one infection are typically treated for both by their health care provider.
- To prevent health complications and sexual transmission, treatment should be provided promptly for all persons testing positive for infection, and recent sexual partners should be treated at the same time to prevent reinfection.
- Infected individuals should follow their health care provider's recommendations about how long to abstain from sex after the treatment is completed to avoid passing the infection back and forth.
Gonorrhea
- Caused by the bacterium Neisseria gonorrhoeae, which can grow and multiply rapidly in the warm, moist areas of the reproductive tract
- Most common symptoms include discharge from the vagina or penis and painful or difficult urination.
- Can be treated with antibiotics
- Like chlamydia, if left untreated, gonorrhea can cause pelvic inflammatory disease, which can lead to chronic pelvic pain and permanent damage to a woman's reproductive organs. This damage may lead to ectopic pregnancy (in which the fetus develops outside of the womb, a condition that can be life-threatening) and infertility.
- In both men and women, gonorrhea can also infect the mouth, throat, eyes, and rectum and can spread to the blood and joints, where it can become a life-threatening illness.
- Can be transmitted to the fetus during pregnancy
- Because chlamydia and gonorrhea often occur together, people who have one infection are typically treated for both by their health care provider.
- To prevent health complications and sexual transmission, treatment should be provided promptly for all persons testing positive for infection, and recent sexual partners should be treated at the same time to prevent reinfection.
- People with gonorrhea can more easily contract HIV, the virus that causes AIDS. HIV-infected people with gonorrhea are also more likely to transmit the virus to someone else.
Genital Herpes
- Caused by the herpes simplex virus (HSV)
- There are two different strains, or types: HSV type 1 (HSV-1) and type 2 (HSV-2). Both can cause genital herpes, although most cases of genital herpes are caused by HSV-2.
- Symptoms of HSV-1 usually appear as fever blisters or cold sores on the lips, but it can also infect the genital region through oral-genital or genital-genital contact. Symptoms of HSV-2 are typically painful, watery skin blisters on or around the genitals or anus. However, substantial numbers of people who carry these viruses have no or only minimal signs or symptoms.
- Cannot be cured, but can be controlled with medication
- One medication can be taken daily to make it less likely that the infection will pass on to sex partner(s) or to infants during childbirth.
- Periodically, some people will experience outbreaks of symptoms in which new blisters form on the skin in the genital area; at those times, the virus is more likely to be passed on to other people.
- If a pregnant woman has an outbreak when she goes into labor, she may need to have a cesarean section (C-section) to prevent the infant from getting the virus during birth.
- Pregnant women, especially those who acquire genital herpes for the first time during pregnancy, may pass the infection to their newborns, causing life-threatening neonatal HSV, an infection affecting the infant's skin, brain, and other organs.
HIV/AIDS
- HIV, human immunodeficiency virus, is the virus that causes AIDS.
- Destroys the body's immune system by killing the blood cells that fight infection. Once HIV destroys a substantial proportion of these cells, the body's ability to fight off and recover from infections is compromised. This advanced stage of HIV infection is known as AIDS.
- People whose HIV infection has progressed to AIDS have a weakened immune system and are very susceptible to opportunistic infections that do not normally make people sick and to certain forms of cancer.
- In people who do not have HIV, the infection can be prevented by many tools, including abstaining from sex, limiting the number of sexual partners, never sharing needles, and using condoms appropriately. Persons who may be at very high risk of HIV infection may be able to obtain HIV Pre-Exposure Prophylaxis or PrEP, which consists of the HIV medication called Truvada, from their doctor to take every day so they can prevent HIV infection. PrEP will not work if it is not taken consistently.
- AIDS can be prevented in those with HIV infection by early initiation of antiretroviral therapy.
- Transmission of the virus primarily occurs during unprotected sexual activity and by sharing needles used to inject intravenous drugs.
- HIV can also spread from mother to fetus during pregnancy and from mother to infant during delivery and breastfeeding. However, treatments are available that can virtually eliminate these types of transmission.
Human Papillomavirus (HPV)
- HPV is the most common STI. More than 40 HPV types exist, and all of them can infect both men and women.
- The types of HPVs vary in their ability to cause genital warts; infect other regions of the body, including the mouth and throat; and cause cancers of the cervix, vulva, penis, anus, and mouth.
- Cannot be cured but can be prevented with vaccines and controlled with medications
- Genital warts caused by the virus can also be treated.
- Regular screening with a Pap smear test can prevent or detect at an early stage most cases of HPV-caused cervical cancer. (A Pap smear test involves a health care provider taking samples of cells from the cervix during a standard gynecologic exam; these cells are examined under a microscope for signs of developing cancer).
- Two available vaccines protect against most (but not all) HPV types that cause cervical cancer. A group advising the Centers for Disease Control and Prevention recommends this vaccine for boys and girls starting at 11 or 12 years old.
Syphilis
- Caused by the bacterium Treponema pallidum
- Passes from person to person during vaginal, anal, or oral sex through direct contact with syphilis sores
- Syphilis can also be spread from an infected mother to her fetus. In 2001, the number of cases of syphilis was at its lowest in 60 years. But the syphilis rate has increased nearly every year up to 2016, the most recent year for which data are available. Rates have increased among both men and women, but men account for a vast majority of syphilis cases.
- The first sign of syphilis is a chancre, a painless genital sore that most often appears on the penis or in and around the vagina. Chancres typically resolve on their own, but the body does not clear the infection on its own.
- Chancres make a person two to five times more likely to contract an HIV infection. If the person is already infected with HIV, chancres also increase the likelihood that the HIV virus will be passed on to a sexual partner.
- Can be treated with antibiotics:
- If recognized during the early stages, usually within the first year of infection, syphilis can be treated with a single injection of antibiotic.
- If not recognized early, or not treated immediately, syphilis may need longer treatment with antibiotics.
- Without treatment:
- Usually spreads to other organs, including the skin, heart, blood vessels, liver, bones, and joints in secondary syphilis.
- Other sores, such as a syphilis rash, can break out in later stages.
- Tertiary syphilis can develop over a period of years and involve the nerves, eyes, and brain and can potentially cause death.
- Can pass to the fetus during pregnancy and to the infant during delivery
- Infants who get syphilis infection in the womb may have misshapen bones, very low red blood cell count (called severe anemia), enlarged liver and spleen, jaundice (yellowing of the skin or eyes), nerve problems, blindness or deafness, meningitis, and skin rashes.
- Those being treated for syphilis must avoid sexual contact until the syphilis sores are completely healed to avoid infecting other people.
- Persons with syphilis must notify their sex partners so that they also can be tested and receive treatment if necessary.
- Pregnant women with syphilis, especially untreated syphilis, are at an increased risk of miscarriage and stillbirth.
Bacterial Vaginosis
- Occurs when problematic bacteria that are normally present only in small amounts in the body increase in number. Their levels get so high that they replace normal vaginal bacteria and upset the usual balance.
- More likely if a woman douches frequently or has new or multiple sexual partners
- Most common symptom is a thin, milky discharge that is often described as having a "fishy" odor. However, some women will have no symptoms at all.
- Can be treated with antibiotics, typically metronidazole or clindamycin
- Generally, sexual partners of women with bacterial vaginosis do not need to be treated because treatment of partners has not been shown to reduce the risk of recurrence.
- Treatment is recommended for all pregnant women who show symptoms.
- Increases the risk of getting other STIs even if the woman doesn't have any symptoms
- Associated with preterm labor and birth and having a low birth weight baby
- Also associated with pelvic inflammatory disease, an infection of the female reproductive organs, including the uterus and the fallopian tubes (which carry eggs to the uterus), and with infections that commonly occur after surgery
Trichomoniasis
- Caused by the single-celled parasite Trichomonas vaginalis
- Common in young, sexually active women but also infects men, though less frequently
- The parasite can be transmitted between men and women as well as between women whenever physical contact occurs between the genital areas.
- Can cause frequent, painful, or "burning" urination in men and women as well as vaginal discharge, genital soreness, redness, or itching in women. However, it may not cause any symptoms.
- Because the infection can occur without symptoms, a person may be unaware that he or she is infected and continue to re-infect a sexual partner who is having recurrent signs of infection.
- Can be treated with a single dose of an antibiotic, usually either metronidazole or tinidazole, taken by mouth
- Because of re-infection, it is important to make sure that the diagnosed individual and all sexual partners are treated at the same time.
- Retesting is recommended for all sexually active women within 3 months after initial treatment even if they believe their partners were treated.
- Infection during pregnancy is associated with an increased risk of preterm labor or birth and infants with low birth weight.
- Stillbirth and newborn death are more than twice as likely among pregnant women with Trichomonas infection than among uninfected pregnant women.
Viral Hepatitis
- Caused by several different viral strains
- More information about hepatitis A, B, and C can be found on the Centers for Disease Control and Prevention website.
- Hepatitis A virus (HAV):
- Causes a short-term or self-limited liver infection that can be quite serious.
- Does not result in chronic infection.
- Can be transmitted during sexual activity and through oral-anal contact.
- Vaccination can prevent HAV infection.
- May cause abdominal pain, nausea, and vomiting.
- Usually the infection gets better on its own without requiring treatment. In some cases, however, individuals may have such severe nausea and vomiting that they must be admitted to the hospital or may have lasting damage to their livers.
- Hepatitis B virus (HBV):
- Causes a serious liver infection that can result in both immediate illness and lifelong infection and disease, leading to permanent liver scarring (cirrhosis), cancer, liver failure, and death.
- Can be treated with antiviral medications.
- Vaccination can prevent HBV infection.
- Spreads through sexual contact, as well as through contact with other bodily fluids, such as blood; through shared contaminated needles used for injecting intravenous drugs; and through tattooing and piercing.
- Pregnant women with HBV can transmit the virus to their infants during delivery, but a series of vaccinations and a shot of hepatitis B immune globulin for the baby beginning at birth can prevent this transmission. Without vaccination, babies born to women with HBV infection can develop chronic infection, which can lead to serious health problems.
- People with chronic HBV infection will need to see a liver specialist with experience treating individuals with chronic liver disease. These individuals need to take special care not to pass on the virus to their sexual partners, and sexual partners should receive hepatitis B vaccine if they are not already immune.
- Hepatitis C virus (HCV):
- Serious infection of the liver that can cause an immediate illness but that, in most people, becomes a silent, chronic infection that leads to liver scarring (cirrhosis), cancer, liver failure, and death
- Most infected people may not be aware of their infection because they do not develop symptoms.
- Most commonly transmitted through sharing needles or exposure to infected blood. Less commonly, it can spread through sexual contact or from mother to fetus during pregnancy and delivery.
- Can be treated. New medications seem to be more effective and have fewer side effects than previous options. The Food and Drug Administration maintains a complete list of approved treatments for Hepatitis C.
Zika
- An infection caused by a virus. In most cases, it is spread by mosquitoes, but Zika virus also can be transmitted sexually.
- Zika is usually mild, with symptoms lasting for several days to a week after being infected.
- Research shows that getting Zika during pregnancy can cause birth defects in the developing fetus. In 2015, Zika virus infection was linked to microcephaly—a condition in which the brain and skull are smaller than normal—in newborns, as well as other birth defects.
- Zika also was linked to problems with the adult nervous system, including Guillain-Barré Syndrome.
- Pregnant women should not travel to areas with Zika. If you must travel to one of these areas, talk to your health care provider first and strictly follow steps to prevent mosquito bites during your trip.
- There is currently no specific medication or treatment for Zika infection.
Source: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)