Colorado ranks among the states with the lowest rates when it comes to several common sexually transmitted diseases, as the state’s rates of several STDs, including chlamydia, gonorrhea and syphilis are lower than the overall national rates. However, the news is not all good in our state, as most STDs have seen their prevalence in Colorado rise in recent years, which largely tracks with a national trend in which STD rates have climbed for four straight years.
So which STDs are most common in Colorado, how have rates of some of the most common STDs changed here over time, and how do rates vary depending on the state’s geography? To understand the picture of sexually transmitted diseases and infections in Colorado, let’s examine data from the federal Centers for Disease Control and Prevention as well as the Colorado Department of Public Health & Environment.
Chlamydia Rates in Colorado
More than 26,000 people were diagnosed with chlamydia in Colorado in 2017, putting the state right in the middle when it comes to overall cases. But after adjusting for population size, Colorado drops a few places to No. 30 among the 50 states. Colorado’s chlamydia rate is about 8% lower than the overall U.S. rate.
Chlamydia infections per 100,000 people, bottom 25
While the state’s overall ranking among all states is relatively positive, chlamydia has climbed sharply in Colorado in recent years, jumping nearly 25% since 2008.
Colorado chlamydia rate by year (cases per 100,000 people)
Two Western states, Alaska and New Mexico, are among the top five nationally, but Colorado still ranks in the top half of the region.
Chlamydia infection rate, Western states (cases per 100,000 people)
Gonorrhea Rates in Colorado
Colorado just barely ranks in the bottom half of all states when it comes to the prevalence of gonorrhea in our state. Colorado’s population-adjusted gonorrhea rate is about 12% lower than the overall national rate.
Gonorrhea infections per 100,000 people
Colorado has seen a huge explosion in the gonorrhea rate with a one-year increase of nearly 40% between 2016 and 2017 and a 97% increase over the past 10 years.
Colorado gonorrhea rate by year (cases per 100,000 people)
Colorado ranks in the top half regionally when it comes to the prevalence of gonorrhea, though the state’s rate is just over half that of Alaska, the regional leader and No. 2 state overall.
Gonorrhea infection rate, Western states (cases per 100,000 people)
Syphilis Rates in Colorado
Colorado comes in 33rd overall nationally in the population-adjusted rate of infections of primary and secondary syphilis, and the state’s rate is just over half the overall U.S. rate.
Primary and secondary syphilis infections per 100,000 people, bottom 25
Syphilis has made a roaring comeback in the state after rates dipped into the low single digits. Since 2008, the infection rate of primary and secondary syphilis has doubled in Colorado.
Colorado primary and secondary syphilis rate by year (cases per 100,000 people)
Colorado’s syphilis rate places the state in the bottom half among regional neighbors, far behind regional and overall national leader, Nevada.
Primary and secondary syphilis infection rates, Western states (cases per 100,000 people)
HIV & Other STD Rates in Colorado
Nearly 450 people were newly diagnosed with HIV in Colorado in 2017, and the state is 24th overall in population-adjusted HIV rates. But Colorado is one of only 18 states to see an increase in the prevalence of HIV between 2016 and 2017, though the increase (3%) was slight. See Best Ways to Test for HIV
Hepatitis B & C
Acute infections of both hepatitis B and hepatitis C are less common in Colorado than in the United States overall. Acute hep C cases occur at a rate about 40% lower in Colorado than in the rest of the country, and hep C infections have dropped slightly in recent years. Hep B occurs at about half the national rate in Colorado, and the rate has remained steady over the past five years. See Best Ways to Test for Hepatitis C
Colorado has the sixth-lowest rate of cancers related to human papillomavirus, which, in addition to being the most common STD in the world, is also the primary cause of several types of cancer, most famously cervical cancer. HPV-related cancers occur in Colorado at a rate of 10.3 per 100,000, compared to the national median of 11.7 per 100,000. Pinpointing exactly how many people in Colorado have HPV at any given time is difficult because the virus rarely causes symptoms, but untreated HPV can be devastating, including leading to cervical and other cancers, such as penile and anal cancer. See Best Ways to Test for HPV
STDs in Colorado Cities & Counties
While the state generally ranks relatively low nationally, several locales in Colorado have much higher rates of STDs than the state of Colorado, particularly the city of Denver.
Denver accounted for about 1 in 4 chlamydia cases in Colorado in 2017.
Colorado counties by chlamydia infection rate (cases per 100,000 people), top 10
More than a third of all gonorrhea cases were diagnosed among those living in Denver in 2017.
Colorado counties by gonorrhea infection rate (cases per 100,000 people), top 10
Primary and secondary syphilis
Nearly half of all infections of primary and secondary syphilis in Colorado in 2017 were among those living in Denver.
Colorado counties by primary and secondary syphilis infection rate (cases per 100,000 people)
Colorado isn’t among the states with the highest rates of some of the most common sexually transmitted infections, but that’s no reason for complacency if you live in Colorado. That’s because rates of most sexually transmitted infections and diseases are going up in our state, and most people who are infected aren’t aware of it, which is why it’s so easy to pass STDs along to sexual partners. The best way to be sure you aren’t doing that is to get tested so you can find out what your STD status is.
- Colorado Department of Public Health & Environment, Sexually Transmitted Infections in Colorado. (2018). Retrieved from https://drive.google.com/file/d/1qbSV-o3JMXEOuuOLRdXWY-K1PVOfgpjy/view
- Centers for Disease Control and Prevention, HIV Surveillance Report, Diagnoses of HIV Infection in the United States and Dependent Areas, 2017. (2018). Retrieved from https://www.cdc.gov/hiv/pdf/library/reports/surveillance/cdc-hiv-surveillance-report-2017-vol-29.pdf
- Centers for Disease Control and Prevention, Sexually Transmitted Disease Surveillance 2017. (2018). Retrieved from https://www.cdc.gov/std/stats17/SRtables.pdf
- Centers for Disease Control and Prevention, Surveillance for Viral Hepatitis – United States, 2016. (2018). Retrieved from https://www.cdc.gov/hepatitis/statistics/2016surveillance/index.htm
- Centers for Disease Control and Prevention, HPV-Associated Cancer Rates by State, 2011-2015. (2018). Retrieved from https://www.cdc.gov/cancer/hpv/statistics/state/index.htm
Note: Some states have published more recent data for chlamydia, gonorrhea, and primary and secondary syphilis. For states in which that’s the case, we have substituted the individual state data for 2018 and used that in our rankings, while other states’ rankings are based on 2017 numbers. In some cases, we assume that when the full national dataset is published by the CDC, states’ positions relative to other states will change some, though those changes are unlikely to be dramatic, since the CDC data comes from the states.