Sexually Transmitted Diseases

Bacteria and Viruses

Sexually transmitted diseases are caused by a variety of bacterial and viral pathogens, and those infected can present with a range of symptoms. One of the most common sexually transmitted infections, chlamydia, is caused by the Chlamydia trachomatis bacteria and can cause painful urination, fever, unusual discharge or bleeding from the genitals, and abdominal pain. Chlamydia is often referred to as a “silent infection,” however, as up to half of males and three-quarters of females who are infected do not exhibit symptoms and do not know they are infected. Among women who are asymptomatic, approximately half who are not treated will developed pelvic inflammatory disorder (PID), which can cause scarring in the fallopian tubes, uterus, and ovaries, and can cause serious complications including chronic pelvic pain and complications in pregnancy.

Gonorrhea, another bacterial sexually transmitted infection, is caused by the Neisseria gonorrhoeae bacteria and can also result in pelvic inflammatory disorder, as well as infections of the urethra, cervix, uterus, epididymis, and testicles. Symptoms include painful urination and intercourse, discharge or bleeding from the genitals, cramps, vomiting, fever, and scrotal swelling. As with chlamydia, up to two-thirds of those infected with gonorrhea may be asymptomatic. These asymptomatic infections, which can lead to other reproductive health problems, are an important reason why sexually active people should be routinely screened for sexually transmitted pathogens, even when they exhibit no symptoms.

Syphilis is also a bacterial sexually transmitted disease, caused by the Treponema pallidum bacteria. Primary syphilis occurs 10 to 90 days following infection, and patients experience a single sore near the site of infection. Secondary syphilis occurs one to six months following infection, and is characterized by a skin rash on the trunk and extremities (including the palms of hands and soles of feet), fever, sore throat, headache, weight loss, and enlarged lymph nodes. Tertiary syphilis occurs 1 to 50 years following secondary syphilis, and is characterized by tumor-like growths on the skin, mucous membranes, skeleton, and elsewhere. If left untreated, tertiary syphilis can cause damage to the heart, brain, and nervous system, and can be fatal. Syphilis gained notoriety in the United States in the course of one of the most unethical medical experiments involving human subjects, the Tuskegee Syphilis Study, during which infected Af-rican-American men were left untreated in order to study the natural course of the disease, even though effective antibiotics had long been available.

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