Sexually transmitted diseases (STDs) are generally acquired by sexual contact. The organisms (bacteria, viruses or parasites) 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 non-sexually, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

Symptoms

Sexually transmitted diseases (STDs) 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
• Fever
• 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.

Causes

• Bacteria (gonorrhea, syphilis, chlamydia)
• Parasites (trichomoniasis)
• Viruses (human papillomavirus, genital herpes, HIV)

Risk factors

• Having unprotected sex
• Having sexual contact with multiple partners.
• 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 see a doctor as soon as possible so that you can receive screening, treatment and emotional support.
• Misuse of alcohol or use of recreational drugs. Substance misuse can inhibit your judgment, making you more willing to participate in risky behaviors.
• Injecting drugs. Needle sharing spreads many serious infections, including HIV, hepatitis B and hepatitis C.

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 or even death. All pregnant women should be screened for these infections and treated.

Complications

Because many people in the early stages of a sexually transmitted disease (STD) or sexually transmitted infection (STI) experience no symptoms, screening for STIs is important in preventing complications.

Possible complications include:

• Pelvic pain
• Pregnancy complications
• Eye inflammation
• Arthritis
• Pelvic inflammatory disease
• Infertility
• Heart disease
• Certain cancers, such as HPV-associated cervical and rectal cancers