Sexually transmitted infections (STIs) are diseases transmitted primarily through unsafe sexual interactions. Bacteria, viruses, or parasites cause them and can result in severe health complications if untreated.

Chlamydia

The bacterium Chlamydia trachomatis is responsible for the disease Chlamydia, the most common STI in the United States. This peculiar pathogen requires human cells to reproduce, residing intracellularly. The initial infection often goes unnoticed because it typically does not present symptoms. In men, it can lead to urethritis with symptoms such as mild to severe discharge, a burning sensation during urination, and the urge to urinate frequently, which, if untreated, can result in inflamed epididymides and eventually infertility. Women also might not show symptoms in up to 70% of cases, yet Chlamydia stands as the principal cause of pelvic inflammatory disease. It can cause inflammation of the fallopian tubes, leading to a higher risk of ectopic pregnancies and sterility due to scarring.

Trichomoniasis

Trichomoniasis is among the most prevalent and treatable STIs resulting from the Trichomonas vaginalis protozoan. T. vaginalis is a motile organism that resides in the lower genitourinary tract of women and the prostate and urethra of men, and infection occurs when it proliferates abnormally. Many individuals with the disease do not exhibit symptoms; however, those who do might notice itching, burning sensations, general discomfort, and an unusual odorous discharge in women, with men experiencing irritations and slight discharge. Trichomoniasis may also heighten the risk of contracting other STIs, including HIV and gonorrhea.

Gonorrhea

Another common bacterial STI is Gonorrhea, colloquially called "the clap," caused by Neisseria gonorrhoeae. Affecting mainly the 15 to 29 age group, it results in an estimated 1 to 2 million new cases annually in the U.S. The passing of the infection can occur during various forms of sexual intercourse, including oral-genital, and can also spread to newborns during childbirth. Symptoms in men are typically more noticeable, with a thick pus-like discharge and painful urination, whereas 50% of infected women may initially experience no symptoms. The disease can advance unnoticed to a more severe stage, potentially leading to infertility in women due to pelvic inflammatory disease, which may obstruct the fallopian tubes with scar tissue. In newborns, gonorrhea acquired during childbirth can lead to neonatal conjunctivitis, a severe eye infection that may result in blindness. However, prophylactic measures, such as the application of erythromycin ointment to the eyes of newborns, have replaced the older use of 1% silver nitrate solution and are now the standard preventive treatment.

Syphilis

Syphilis is an STI instigated by Treponema pallidum and can be transmitted during sexual contact, through blood, or from mother to fetus via the placenta. This infection has distinct stages, beginning with a primary stage characterized by a non-painful sore, or chancre, which heals within a few weeks. Subsequent stages spread systemically to various organs, with secondary symptoms like rash and fever appearing weeks to months later. Severe damage and symptoms, particularly to the nervous system, define the tertiary stage, which can include loss of motor control and cognitive impairments ranging from mood swings to advanced hallucinations. Tertiary syphilis can also affect the cardiovascular system, leading to aortitis.

Genital Herpes

Genital Herpes is an incurable STI chiefly caused by the Type II herpes simplex virus (HSV-2). This virus causes painful blisters in the genital regions in both genders. The virus remains dormant within the body, leading to periodic reactivation and symptom recurrence. A related Type I herpes simplex virus (HSV-1) usually results in cold sores around the mouth.

Genital Warts

Caused by various strains of the human papillomavirus (HPV), genital warts manifest as growths or protrusions in the genital area. They can develop as isolated lumps or clusters resembling cauliflowers. Nearly one million Americans face this condition yearly. Transmission occurs sexually, and symptoms may manifest long after contact with an asymptomatic carrier. While the immune system often controls HPV naturally, persistent warts signal ineffective viral control. Though there is no definitive cure, topical treatments can manage the condition. Topical treatments for genital warts include Podofilox, a gel or cream that destroys wart tissue by inhibiting cell division, and Sinecatechins, a green tea extract-based ointment for external genital and perianal warts.

HIV

HIV (human immunodeficiency virus) is a sexually transmitted infection (STI) spread through bodily fluids during unprotected sexual contact. It targets the immune system, weakening the body’s defenses and, if untreated, progressing to AIDS (acquired immunodeficiency syndrome). HIV can also spread through contaminated needles, blood transfusions, and from mother to child. Prevention measures, such as condom use, significantly reduce transmission risk, while regular STI testing helps early detection and timely intervention Early diagnosis and antiretroviral therapy (ART) are essential for managing HIV, maintaining immune health, preventing progression to AIDS, and reducing chances of transmission.