Sexually Transmitted Infections: Causes, Symptoms, Testing and Prevention

How they spread

STIs are transmitted in several ways. Direct contact with infected genital skin, sores, or fluids is the main route. Specific sexual activities that can transmit infections include oral sex and anal sex. In addition, some infections can pass through shared needles, blood exposure, or from an infected parent to a child around the time of birth or during breastfeeding.

Causes

Different organisms cause STIs. Some are caused by viruses, others by bacteria, and some by parasites. Which type of organism is responsible determines the options for testing and treatment.

Signs, testing, and care

Many STIs produce symptoms such as unusual discharge, pain when urinating, genital sores or rashes, or pelvic pain, but a large proportion of infections can be asymptomatic. Because symptoms may be absent or mild, regular testing is important for people who are sexually active, especially with new or multiple partners. Testing and treatment are available through clinics and healthcare providers; early care reduces the risk of complications and of passing an infection to others.

Prevention and treatment

• Consistent and correct use of barrier methods (for example, condoms) reduces but does not eliminate risk.
• Vaccination is effective for some viral infections (for example, vaccines exist for human papillomavirus and hepatitis B).
• Bacterial STIs can often be cured with antibiotics when diagnosed promptly.
• Many viral infections cannot be cured but can be managed with antiviral medicines and other care to reduce complications and transmission.
• Regular screening, treating partners when needed, and open communication with healthcare providers help control spread.

Common infections

• Chlamydia – a common bacterial infection that may be asymptomatic but can be treated with antibiotics.
• Gonorrhea – another bacterial STI that requires medical diagnosis and antibiotic therapy.
• Syphilis – a bacterial infection with distinct stages; early detection and antibiotic treatment are important.
• Human papillomavirus (HPV) – a group of viruses some of which can cause genital warts or lead to cancers; vaccines can prevent the most dangerous types.
• Genital herpes – caused by herpes simplex viruses; symptoms can be managed but the virus persists in the body.
• Human immunodeficiency virus (HIV) – a virus that attacks the immune system; modern antiretroviral treatment controls the infection and prevents progression to AIDS.
• Trichomoniasis and ectoparasites (for example, pubic lice) – parasitic infections that may be treated with specific medications.

If you are concerned about exposure, notice symptoms, or are unsure about your risk, seek testing and advice from a healthcare provider. Early diagnosis and appropriate care protect your health and the health of your partners.