Sexually transmitted diseases (STDs) are generally acquired by sexual contact. The organisms that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids.
Sometimes these infections can be transmitted nonsexually, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.
It’s possible to contract sexually transmitted diseases from people who seem perfectly healthy, and who may not even be aware of the infection. STDs don’t always cause symptoms, which is one of the reasons experts prefer the term “sexually transmitted infections” to “sexually transmitted diseases.”
Sexually transmitted infections (STIs) can have a range of signs and symptoms, including no symptoms. That’s why they may go unnoticed until complications occur or a partner is diagnosed. Signs and symptoms that might indicate an STI include:
- Sores or bumps on the genitals or in the oral or rectal area
- Painful or burning urination
- Discharge from the penis
- Unusual or odd-smelling vaginal discharge
- Unusual vaginal bleeding
- Pain during sex
- Sore, swollen lymph nodes, particularly in the groin but sometimes more widespread
- Lower abdominal pain
- Rash over the trunk, hands or feet
Signs and symptoms may appear a few days after exposure, or it may take years before you have any noticeable problems, depending on the organism.
Sexually transmitted infections can be caused by:
- Bacteria (gonorrhea, syphilis, chlamydia)
- Parasites (trichomoniasis)
- Viruses (human papillomavirus, genital herpes, HIV)
Sexual activity plays a role in spreading many other infectious agents, although it’s possible to be infected without sexual contact. Examples include the hepatitis A, B and C viruses, shigella, and Giardia intestinalis.
- Having unprotected sex. Vaginal or anal penetration by an infected partner who isn’t wearing a latex condom significantly increases the risk of getting an STI. Improper or inconsistent use of condoms can also increase your risk.Oral sex may be less risky, but infections can still be transmitted without a latex condom or dental dam. Dental dams — thin, square pieces of rubber made with latex or silicone — prevent skin-to-skin contact.
- Having sexual contact with multiple partners. The more people you have sexual contact with, the greater your risk. This is true for concurrent partners as well as monogamous consecutive relationships.
- Having a history of STIs. Having one STI makes it much easier for another STI to take hold.
- Anyone forced to have sexual intercourse or sexual activity. Dealing with rape or assault can be difficult, but it’s important to be seen as soon as possible. Screening, treatment and emotional support can be offered.
- Injecting drugs. Needle sharing spreads many serious infections, including HIV, hepatitis B and hepatitis C.
- Being young. Half of STIs occur in people between the ages of 15 and 24.
- Men who request prescriptions for drugs to treat erectile dysfunction. Men who ask their doctors for prescriptions for certain drugs — such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) — have higher rates of STIs. Be sure you are up to date on safe sex practices if you ask your doctor for one of these medications.
Transmission from mother to infant
Certain STIs — such as gonorrhea, chlamydia, HIV and syphilis — can be passed from an infected mother to her child during pregnancy or delivery. STIs in infants can cause serious problems and may be fatal. All pregnant women should be screened for these infections and treated.
Because many people in the early stages of an STI experience no symptoms, screening for STIs is important in preventing complications.
Possible complications include:
- Pelvic pain
- Pregnancy complications
- Eye inflammation
- Pelvic inflammatory disease
- Heart disease
- Certain cancers, such as HPV-associated cervical and rectal cancers
There are several ways to avoid or reduce your risk of sexually transmitted infections.
- Abstain. The most effective way to avoid STIs is to abstain from sex.
- Stay with one uninfected partner. Another reliable way of avoiding STIs is to stay in a long-term mutually monogamous relationship with a partner who isn’t infected.
- Wait and verify. Avoid vaginal and anal intercourse with new partners until you have both been tested for STIs. Oral sex is less risky, but use a latex condom or dental dam — a thin, square piece of rubber made with latex or silicone — to prevent direct contact between the oral and genital mucous membranes. Keep in mind that no good screening test exists for genital herpes for either sex, and human papillomavirus (HPV) screening isn’t available for men.
- Get vaccinated. Getting vaccinated early, before sexual exposure, is also effective in preventing certain types of STIs. Vaccines are available to prevent human papillomavirus (HPV), hepatitis A and hepatitis B.The Centers for Disease Control and Prevention (CDC) recommends the HPV vaccine for girls and boys ages 11 and 12. If not fully vaccinated at ages 11 and 12, the CDC recommends that girls and women through age 26 and boys and men through age 26 receive the vaccine.The hepatitis B vaccine is usually given to newborns, and the hepatitis A vaccine is recommended for 1-year-olds.
Use condoms and dental dams consistently and correctly.
- Use a new latex condom or dental dam for each sex act, whether oral, vaginal or anal. Never use an oil-based lubricant, such as petroleum jelly, with a latex condom or dental dam.Condoms made from natural membranes are not recommended because they’re not as effective at preventing STIs. Keep in mind that while condoms reduce your risk of exposure to most STIs, they provide a lesser degree of protection for STIs involving exposed genital sores, such as human papillomavirus (HPV) or herpes. Also, nonbarrier forms of contraception, such as oral contraceptives or intrauterine devices, don’t protect against STIs.
- Don’t drink alcohol excessively or use drugs. If you’re under the influence, you’re more likely to take sexual risks.
- Communicate. Before any serious sexual contact, communicate with your partner about practicing safer sex. Reach an explicit agreement about what activities will and won’t be OK.
- Consider male circumcision. There’s evidence that male circumcision can help reduce a man’s risk of acquiring HIV from an infected woman (heterosexual transmission) by as much as 60 percent. Male circumcision may also help prevent transmission of genital HPV and genital herpes.
Consider the drug Truvada.
- In July 2012, the Food and Drug Administration approved the use of the combination drug emtricitabine-tenofovir (Truvada) to reduce the risk of sexually transmitted HIV infection in those who are at high risk. Truvada is also used as an HIV treatment along with other medications.When used to help prevent HIV infection, Truvada is only appropriate if your doctor is certain you don’t already have HIV infection.Your doctor should also test for hepatitis B infection. If you don’t have hepatitis B, your doctor may recommend the hepatitis B vaccine if you haven’t had it yet. If you have hepatitis B, your doctor should test your kidney function before prescribing Truvada.
Truvada must be taken daily, exactly as prescribed, and you’ll need follow-up HIV and kidney function testing every few months. Truvada should only be used along with other prevention strategies such as condom use every time you have sex.
If your sexual history and current signs and symptoms suggest that you have an STI, laboratory tests can identify the cause and detect coinfections you might have contracted.
- Blood tests. Blood tests can confirm the diagnosis of HIV or later stages of syphilis.
- Urine samples. Some STIs can be confirmed with a urine sample.
- Fluid samples. If you have active genital sores, testing fluid and samples from the sores may be done to diagnose the type of infection. Laboratory tests of material from a genital sore or discharge are used to diagnose some STIs.
- Everyone. The one STI screening test suggested for everyone ages 13 to 64 is a blood or saliva test for human immunodeficiency virus (HIV), the virus that causes AIDS.
Everyone born between 1945 and 1965. There’s a high incidence of hepatitis C in people born between 1945 and 1965. Since the disease often causes no symptoms until it’s advanced, experts recommend that everyone in that age group be screened for hepatitis C.
- Pregnant women. Screening for HIV, hepatitis B, chlamydia and syphilis generally takes place at the first prenatal visit for all pregnant women. Gonorrhea and hepatitis C screening tests are recommended at least once during pregnancy for women at high risk of these infections.
- Women age 21 and older. The Pap test screens for cervical abnormalities, including inflammation, precancerous changes and cancer, which is often caused by certain strains of human papillomavirus (HPV). Experts recommend that starting at age 21, women should have a Pap test at least every three years. After age 30, women are advised to have an HPV DNA test and a Pap test every five years or a Pap test every three years.
- Women under age 25 who are sexually active. All sexually active women under age 25 should be tested for chlamydia infection. The chlamydia test uses a sample of urine or vaginal fluid you can collect yourself. Some experts recommend repeating the chlamydia test three months after you’ve had a positive test and been treated.
The second test is needed to confirm that the infection is cured as reinfection by an untreated or undertreated partner is common. Screening for gonorrhea also is recommended in sexually active women under age 25.
- Men who have sex with men. Compared with other groups, men who have sex with men run a higher risk of acquiring STIs. Many public health groups recommend annual or more frequent STI screening for these men. Regular tests for HIV, syphilis, chlamydia and gonorrhea are particularly important. Evaluation for hepatitis B also may be recommended.
- People with HIV. If you have HIV, it dramatically raises your risk of catching other STIs. Experts recommend immediate testing for syphilis, gonorrhea, chlamydia and herpes after being diagnosed with HIV. People with HIV should also be screened for hepatitis C.Women with HIV may develop aggressive cervical cancer, so they should have a Pap test within a year of being diagnosed with HIV, and then again six months later.
- People who have a new partner. Before having vaginal or anal intercourse with new partners, be sure you’ve both been tested for STIs. Keep in mind that human papillomavirus (HPV) screening isn’t available for men. No good screening test exists for genital herpes for either sex, so you may not be aware you’re infected until you have symptoms.
STIs caused by bacteria are generally easier to treat. Viral infections can be managed but not always cured. If you’re pregnant and have an STI, prompt treatment can prevent or reduce the risk of infection of your baby.
- Antibiotics. Antibiotics, often in a single dose, can cure many sexually transmitted bacterial and parasitic infections, including gonorrhea, syphilis, chlamydia and trichomoniasis. Typically, you’ll be treated for gonorrhea and chlamydia at the same time because the two infections often appear together.Once you start antibiotic treatment, it’s crucial to follow through. If you don’t think you’ll be able to take medication as prescribed, tell your doctor. A shorter, simpler treatment regimen may be available.In addition, it’s important to abstain from sex until you’ve completed treatment and any sores have healed.
- Antiviral drugs. You’ll have fewer herpes recurrences if you take daily suppressive therapy with a prescription antiviral drug. Antiviral drugs lessen the risk of infection, but it’s still possible to give your partner herpes.Antiviral drugs can keep HIV infection in check for many years. Virus persists and can still be transmitted, though the risk is lower.The sooner you start treatment, the more effective it is. Once you start treatment — if you take your medications exactly as directed — it’s possible to lower your virus count to nearly undetectable levels.