How common are STDs in the US?

The CDC estimates that one in five Americans has an STD. Young adults from ages 20 to 34 have the highest rates of infection.

Updated on Fri, September 1, 2023 by the USAFacts Team

The Centers for Disease Control and Prevention’s (CDC) 2021 STD Surveillance Report indicates cases of sexually transmitted diseases decreased during the early months of the pandemic, but most resurged by the end of the year and into 2021.

The CDC report also highlighted how STD rates (number of infections per 100,000 people) vary by state, age, and sex. Here's a deeper look at that data.

What are STDs?

STDs, or sexually transmitted diseases, are infections that are primarily spread through sexual contact. These diseases affect both men and women and are caused by bacteria, viruses, parasites, or other microorganisms. STDs can be transmitted through vaginal, anal, or oral sex, or from mother to child during childbirth or breastfeeding.

STDs are also commonly referred to as STIs (sexually transmitted infections).

Which STDs are tracked by the CDC?

The CDC tracks reported cases of chlamydia, gonorrhea, syphilis, and congenital syphilis.

Human papillomavirus, or HPV, is the most common STD in the nation, but most people with the infection have no symptoms, and no national case-reporting system for HPV infections exists.

Of the STDs tracked by the CDC, chlamydia makes up the largest proportion of cases in the US, with over 1.6 million cases (496 cases per 100,000 people) reported to the CDC in 2021.