Learn About STIs

Chlamydia infection is a common bacterial infection in the US, with the highest rate among people aged 24 or younger. It is curable when treated with antibiotics. Chlamydia is often called the "silent infection" because many infected individuals do not experience any symptoms; early detection and treatment are important to prevent progression and avoid spreading to others.

In the US nearly 1.6 million new gonorrhea infections occur each year, making gonorrhea the second most commonly reported sexually transmitted infection. It is a bacterial infection that can grow in the genital tracts, mouth, throat, eyes and anus. Many people—especially women—do not experience symptoms, so regular testing and early treatment are important. The first symptoms usually appear within 10 days after exposure, but some people may be infected for months before signs emerge. Women are often asymptomatic until complications such as pelvic inflammatory disease occur, which can lead to infertility or ectopic pregnancy.

Hepatitis B is a viral infection that primarily affects the liver. It is caused by the hepatitis B virus (HBV) and is transmitted through contact with infected blood or other bodily fluids. A vaccine protects against HBV. Infection can be acute or chronic and can lead to serious health problems including liver disease, cirrhosis, liver failure, liver cancer and death.

Hepatitis C is a viral infection caused by the hepatitis C virus (HCV). It affects the liver and can lead to serious inflammation and damage. The World Health Organization estimates that around 71 million people worldwide have chronic hepatitis C, and it is the most common chronic blood‑borne infection in the United States with about 2.4 million people living with the disease.

Genital herpes is a common sexually transmitted infection caused by the herpes simplex virus (HSV). The CDC estimated there were 572,000 new genital herpes infections in the United States in a single year. Type 1 (HSV‑1) generally affects the lips and mouth, while genital herpes is usually caused by type 2. The virus is spread through sexual contact, including vaginal, anal and oral sex.

Human Immunodeficiency Virus (HIV) is a viral infection that attacks the immune system, which normally fights off infections and diseases. HIV is transmitted through contact with infected bodily fluids such as blood, semen, vaginal secretions and breast milk. Without treatment HIV can progress to Acquired Immune Deficiency Syndrome (AIDS); there is currently no cure for HIV/AIDS.

Human papillomavirus (HPV) is the most common sexually transmitted infection caused by the human papillomavirus. There are more than 100 types of HPV; some cause warts and others can cause different types of cancer.

Syphilis is a highly contagious sexually transmitted infection caused by the bacterium Treponema pallidum. It is a serious and chronic disease that can cause severe health problems if left untreated. In 2020 the CDC reported 133,945 cases of syphilis across all stages.

Trichomoniasis ("trich") is a sexually transmitted infection caused by the parasite Trichomonas vaginalis. The CDC estimated that more than 2 million people in the United States were infected in 2018. Trichomoniasis is more common in women than in men, and many infected people do not experience symptoms. Without treatment, trich can increase the risk of acquiring or spreading other sexually transmitted diseases.