Sexually Transmitted Infections

I

Introduction

Sexually Transmitted Infections (STIs), formerly known as venereal diseases, more than 25 infections passed from one person to another primarily during sexual contact. STIs are among the most common infections known—more than 15 million people in the United States become infected with one or more STIs every year. The United States has the highest STI rate in the industrialized world—roughly half of all Americans become infected with an STI before the age of 35. Despite the prevalence of STIs, studies show that many people are unaware of their risks for contracting an STI or the serious, and sometimes deadly, health consequences that may result from an untreated infection.

Some STIs, such as gonorrhea or chlamydia, may cause no symptoms. People who do not know they are infected risk infecting their sexual partners and, in some cases, their unborn children. If left untreated, these diseases may cause debilitating pain or may destroy a woman’s ability to have children. Some STIs can be cured with a single dose of antibiotics, but many, such as acquired immunodeficiency syndrome (AIDS), are incurable. People with these diseases remain infectious to others for their entire lives.

Those most at risk for contracting STIs are people who have unprotected sex—that is, sex without using a latex or polyurethane condom; those who have multiple partners; and those whose sex partners include intravenous drug users who share needles. Studies show that Americans between the ages of 16 and 24 are at greater risk for acquiring STIs than are older adults because younger people are more likely to have multiple sexual partners rather than a single, long-term relationship. Additionally, young people may be more likely to have unprotected sex and they may find it difficult to tell their sexual partners they are infected with an STI. Young people may also be embarrassed or unable to seek treatment for STIs. This means that they are not only more likely to pass the disease to other young people, they also have a greater risk of suffering the long-term consequences of untreated STIs.

II

How STIs Are Transmitted

STIs are transmitted by infectious agents—microscopic bacteria, viruses, parasites, fungi, and single-celled organisms called protozoa—that thrive in warm, moist environments in the body, such as the genital area, mouth, and throat. Most STIs spread during sexual intercourse (vaginal or anal), but other forms of sexual contact, such as oral sex, can also spread disease.

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Some STIs are transmitted in ways other than by sexual contact. Certain viral STIs, such as AIDS and some types of hepatitis, may be transmitted by contact with infected blood. For instance, viral STIs may pass between people who share infected needles, and a person can become infected from a transfusion of infected blood. Some STIs may pass from an infected mother to her child. Infection may occur before birth, when the infectious agent crosses the placenta (organ in a pregnant woman’s uterus that links the blood supplies of mother and baby) and enters the baby’s bloodstream. Infection also may occur during childbirth, as the baby passes through the birth canal, or after birth, when the baby consumes infected breast milk. STIs cannot be transmitted through shaking hands or other casual contact, or through contact with inanimate objects such as clothing or toilet seats.

III

Common STIs

The most common STIs in the United States include chlamydia, gonorrhea, syphilis, herpes, AIDS, hepatitis, genital warts, and trichomoniasis.

A

Chlamydia

According to the Centers for Disease Control and Prevention (CDC), chlamydia is the most frequently reported infectious disease in the United States. Caused by the Chlamydia trachomatis bacterium, the disease does not produce noticeable symptoms in 75 percent of women and 50 percent of men, so an infection often goes undiagnosed. Experts estimate that 3 million people become infected with chlamydia each year, but according to the CDC, only about 660,000 of these infections are reported each year.

People who do not know they are infected with chlamydia may not seek medical care and they may continue to have sex, unknowingly spreading the disease. When symptoms do develop, men may experience painful or burning urination or a discharge from the penis. Women may experience bleeding between periods, burning urination, vaginal discharge, or mild lower abdominal pain. If left untreated in women, chlamydia can cause severe health problems. Chlamydia damages female reproductive tissue, causing pelvic inflammatory disease (PID). PID can cause chronic, debilitating pelvic pain, infertility, or fatal pregnancy complications. Babies born to mothers infected with chlamydia are at risk of developing eye and lung infections.

Diagnosing chlamydia infections requires a physical examination in which a health-care provider performs a pelvic examination to collect a small amount of vaginal or penile fluid, which is then tested for the presence of Chlamydia trachomatis. New diagnostic tests that use urine samples to identify the presence of the chlamydia bacteria have become available, providing a noninvasive way to diagnose people who show no symptoms for the disease. Chlamydia is treatable with antibiotics.

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