Chlamydia is one of the most common but curable sexually transmitted diseases (STDs), and most people who are infected don’t know they have it. Estimates place the number of new infections in the U.S. at 3 million per year, mostly among those between the ages of 14 and 24.
Who is most likely to contract chlamydia, how has the infection been trending over the years, and where are cases most likely to occur in the United States?
What Is Chlamydia?
Chlamydia is an infection caused by the bacteria chlamydia trachomatis. Though most people who are infected remain asymptomatic, signs of chlamydia vary between men and women:
- Clear or cloudy discharge from tip of penis
- Pain and swelling around testicles
- Painful urination
- Burning and itching on opening of penis
- Abnormal vaginal discharge
- Painful periods
- Painful urination
- Itching or burning around vagina
Only about 1.7 million of the 3 million+ infections of chlamydia are actually reported to healthcare workers because so few people become symptomatic and get themselves tested. The only way to get chlamydia is through sexual contact because the bacteria travels through bodily fluids like semen, pre-cum and vaginal fluids.
It’s not possible to contract chlamydia through casual, non-sexual contact like sharing food or hugging. In rare cases, it’s possible to spread chlamydia to the eyes by touching the area with a hand or finger that’s got infected fluids on it.
Who Is Most Likely to Get Chlamydia?
Sexually active young people are at a very high risk of contracting chlamydia, and about two-thirds of new cases are in people between 15 and 24 years of age. Generally, women are much more likely than men to be diagnosed with chlamydia, though that distinction shifts as people age. Past age 40, more men than women have chlamydia.
Chlamydia infection rates by sex, age 15+ (cases per 100,000 people)
Among racial groups, African-Americans are the most likely to be diagnosed with chlamydia.
Chlamydia infection rates by race, age 15+ (cases per 100,000 people)
|Native American/Alaska Native||781.2|
|Native Hawaiian/Pacific Islander||715.40|
Chlamydia Across the U.S.
The national chlamydia infection rate is 528.8 per 100,000 people, but that rate varies quite widely depending on the state in question. Alaska, for instance, has a rate more than 50% higher than that.
Chlamydia infection rate by state (cases per 100,000 people)
Most states have seen their infection rates for chlamydia go up over the past half-decade, and several states have seen rather large increases that exceed 25%.
Percentage change in chlamydia infection rates (cases per 100,000 people), 2013-2017
In addition to major variation based on the state in question, several cities and metro areas have far higher rates than other cities across the country. Among selected major metropolitan areas, Memphis has the highest of all rates.
Chlamydia rates by metro area (cases per 100,000 population)
|Virginia Beach-Norfolk-Newport News, VA-NC||785.9|
|New Orleans-Metairie, LA||776.3|
|Milwaukee-Waukesha-West Allis, WI||775|
|Austin-Round Rock, TX||632.9|
|San Diego-Carlsbad, CA||627.9|
|San Antonio-New Braunfels, TX||600.1|
|Oklahoma City, OK||597|
|San Francisco-Oakland-Hayward, CA||595.2|
|Atlanta-Sandy Springs-Roswell, GA||590.5|
|Los Angeles-Long Beach-Anaheim, CA||588.3|
|St. Louis, MO-IL||586.7|
|Buffalo-Cheektowaga-Niagara Falls, NY||581.2|
|Kansas City, MO-KS||563.9|
|New York-Newark-Jersey City, NY-NJ-PA||559.7|
|Louisville-Jefferson County, KY-IN||552.1|
|Las Vegas-Henderson-Paradise, NV||551.9|
|Riverside-San Bernardino-Ontario, CA||536.5|
|Houston-The Woodlands-Sugar Land, TX||528.7|
|Dallas-Fort Worth-Arlington, TX||515.2|
|Hartford-West Hartford-East Hartford, CT||509.8|
|Miami-Fort Lauderdale-West Palm Beach, FL||485.1|
|Tampa-St. Petersburg-Clearwater, FL||478.6|
|Minneapolis-St. Paul-Bloomington, MN-WI||475.9|
|Salt Lake City, UT||465|
|San Jose-Sunnyvale-Santa Clara, CA||398.1|
Today, reported chlamydia rates are the highest they’ve ever been in the United States, with a more than 10% increase in the rate of cases in just the past couple of years and a huge increase when zooming even further out.
Chlamydia rates by year (cases per 100,000 population)
Chlamydia rates have risen in the U.S. by nearly 20% in just the past five years, illustrating just how dangerous this STD can be. Often a silent infection, chlamydia can cause pain and discomfort in the rare cases when those infected do have symptoms. But perhaps the worst risk of chlamydia is when it goes untreated and leads to serious health complications. As many as 15% of women with untreated chlamydia go onto develop pelvic inflammatory disease, which can affect a woman’s overall health and ability to reproduce.
The good news is chlamydia is very easily treated and cured with medication, but the first step is finding out your status. If you are among those most likely to have chlamydia (sexually active and under 30), it’s time to get tested.
- Centers for Disease Control and Prevention, Table 2. Chlamydia — Reported Cases and Rates of Reported Cases by State, Ranked by Rates, United States, 2017. (2018). Retrieved from https://www.cdc.gov/std/stats17/tables/2.htm
- Centers for Disease Control and Prevention, Table 10. Chlamydia — Reported Cases and Rates of Reported Cases by Age Group and Sex, United States, 2013–2017. (2018). Retrieved from https://www.cdc.gov/std/stats17/tables/10.htm
- Centers for Disease Control and Prevention, Table 1. Sexually Transmitted Diseases — Reported Cases and Rates of Reported Cases per 100,000 Population, United States, 1941–2017. (2018). Retrieved from https://www.cdc.gov/std/stats17/tables/1.htm