Sexually transmitted diseases (STDs), also referred to as sexually transmitted infections, are on the rise in California and much of the rest of the United States. According to federal data, rates of three of the most common STDs, chlamydia, gonorrhea and syphilis, rose in 2017 for the fourth consecutive year. In California, all of those infections are on the rise, with some rates jumping sharply over the past few years.
Which sexually transmitted disease are most common in the state of California, which regions and cities in the state have the highest rates, and how have infection rates changed in our state over time? Data published by the federal Centers for Disease Control and Prevention and the California Department of Public Health can help shed light.
Chlamydia Rates in California
More than 200,000 new infections of chlamydia occurred in California in 2017, for a population-adjusted rate of 557.4, giving California a rate about 5% higher than the national population-adjusted rate of 528.8.
Chlamydia infections per 100,000 people (top 20)
The state’s chlamydia infection rate has risen every year since 2013 and has more than doubled since 1990.
California chlamydia rate by year (cases per 100,000 people)
California has one of the highest rates of chlamydia in the West, with Arizona the only neighboring state with a higher rate.
Chlamydia infection rate, Western states (cases per 100,000 people)
Gonorrhea Rates in California
More than 75,000 new gonorrhea infections were reported in California in 2017, putting the state in the lead overall. Adjusted for population, California ranks among the 20 states with the highest rate, coming in 13th overall.
Gonorrhea infections per 100,000 people (top 20)
All states have seen their gonorrhea rates rise since 2013, and California’s rate has nearly doubled in that time, going up every year since 2009. After years of decline in the late 1990s, gonorrhea in California today is more prevalent than it was in 1990.
California gonorrhea rate by year (cases per 100,000 people)
California has the third-highest gonorrhea infection rate in the Western region of the U.S., with neighboring Nevada just behind California.
Gonorrhea infection rate, Western states (cases per 100,000 people)
Syphilis Rates in California
Nearly 7,000 cases of syphilis were reported in California in 2017, giving the state by far the highest overall number of total infections. Even when adjusting for the state’s high population and only considering primary and secondary syphilis cases (the two earliest stages), California’s rate of syphilis infections is quite high, ranking second overall in the nation at nearly twice the national rate.
Syphilis infections per 100,000 people (top 20)*
* Primary and secondary syphilis
Syphilis has surged back in the state of California after the rate had dropped into the single digits for more than 20 years. Between 2015 and 2017, primary and secondary syphilis rates rose in California by one-third and have jumped more than 1,600% since 2000.
California primary and secondary syphilis rate by year (cases per 100,000 people)
California and Nevada have by far the highest rates of primary and secondary syphilis in their region.
Syphilis infection rates, Western states (cases per 100,000 people)
HIV & Other STD Rates in California
About 4,300 people were newly diagnosed with HIV in California in 2017, making the state second behind Florida in total number of new HIV diagnoses. When adjusted for population differences, though, California ranks just 14th at a rate of 11.4 per 100,000 people. See Best Ways to Test for HIV
In fact, the state’s 11.4 per 100,000 rate is lower than the national rate of 11.8 per 100,000 people, and California saw its rate of new HIV infections fall nearly 13% between 2016 and 2017.
Hepatitis B & C
Rates of acute infections of both hepatitis B and hepatitis C in California are lower than the national rates. The state’s hep C infection rate has remained steady since 2012, but the rate of acute hep B infections have dropped by 25% in that same time. See Best Ways to Test for Hepatitis C
Human papillomavirus is by far the most common sexually transmitted disease. In fact, it’s so common that almost every sexually active person will get it at some point in their lives. But most people who have HPV are unaware of it, so precise data on the number of Californians living with HPV is scarce. We do know, however, that almost all cervical cancers are caused by HPV and that HPV is a major contributor to many other cancers, such as vaginal, penile and anal cancer. Rates of those cancers are relatively low in California at a rate of just 10.6 per 100,000 people, the ninth-lowest rate in the U.S. See Best Ways to Test for HPV
STD Rates in LA & Other California Cities
California has 24 cities with populations of 200,000 or higher, which often serves to skew figures when it comes to measuring health issues.
More than 40% of chlamydia infections in California in 2017 occurred in just 24 cities.
California cities by chlamydia infection rates (cases per 100,000 people), top 10
More than 1 in 2 gonorrhea cases in California in 2017 were in the 24 biggest cities in the state.
California cities by gonorrhea infection rates (cases per 100,000 people), top 10
Primary, secondary & early latent syphilis
Nearly 60% of syphilis infections diagnosed in the primary, secondary or early latent stages occurred in people who live in the state’s 24 largest cities.
California cities by syphilis infection rates (cases per 100,000 people), top 10
If you’re ever sexually active in your life, it’s likely you will contract at least one sexually transmitted disease, even if you are careful. Not all STDs require the presence of bodily fluids to be transmitted, and many of them show no symptoms at all, so people easily pass them along without even knowing they’ve done so. The good news is most conditions are completely curable, and even the incurable ones respond to treatment that can improve and extend an infection person’s life. Lowering infection rates depends on people knowing their status so they stop the cycle of STDs.
- Centers for Disease Control and Prevention, Sexually Transmitted Disease Surveillance 2017. (2018). Retrieved from https://www.cdc.gov/std/stats17/SRtables.pdf
- California Department of Health, Sexually Transmitted Diseases Control Branch, Sexually Transmitted Diseases Data, All STDs Tables. (2018). Retrieved from https://www.cdph.ca.gov/Programs/CID/DCDC/CDPH%20Document%20Library/STD-Data-All-STDs-Tables.pdf
- 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, HPV-Associated Cancer Rates by State, 2011-2015. (2018). Retrieved from https://www.cdc.gov/cancer/hpv/statistics/state/index.htm
- 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
Note: The CDC publishes comprehensive STD data on only three of the many conditions that are sexually transmitted — chlamydia, gonorrhea, and primary and secondary syphilis. Many other STDs are not classified as nationally notifiable diseases, meaning states are not legally obligated to report infection rates. Also, while the CDC collects data for the District of Columbia, the population density of the district prevents it from being included in rankings.