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)

Alaska 799.8
Louisiana 742.4
Mississippi 707.6
New Mexico 651.6
South Carolina 649.8
Georgia 631.4
North Carolina 619.7
Alabama 615.5
New York 591.6
Illinois 589.9
Arkansas 579.6
Arizona 571.3
Delaware 566.3
California 557.4
Maryland 555.4
Oklahoma 554.4
Nevada 553.1
Texas 543.9
Missouri 536.4
Ohio 528.6
Total 528.8

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)

1990 222
1991 229.7
1992 216.6
1993 218.2
1994 230.8
1995 194.1
1996 192.9
1997 217.2
1998 233.7
1999 253.9
2000 283.6
2001 294.4
2002 317
2003 328.9
2004 345.3
2005 359
2006 376.5
2007 391.3
2008 405
2009 398.1
2010 416.1
2011 437.1
2012 445.9
2013 437.5
2014 449.9
2015 486
2016 504.6
2017 557.4

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)

Alaska 799.8
New Mexico 651.6
Arizona 571.3
California 557.4
Nevada 553.1
Colorado 487.2
Hawaii 479.5
Oregon 455.2
Washington 442.2
Montana 437.4
Idaho 368.4
Wyoming 365.8
Utah 332.2

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)

Mississippi 309.8
Alaska 295.1
Louisiana 256.7
South Carolina 254.4
Alabama 245.7
Oklahoma 231.4
North Carolina 225.4
Arkansas 224.5
Georgia 219.8
New Mexico 215.7
Missouri 214.8
Ohio 206.4
California 190.3
Nevada 187.8
Delaware 187.4
Tennessee 186.8
Illinois 186.4
Maryland 182.5
Arizona 180.4
Indiana 178.4
Total 171.9

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)

1990 181.3
1991 144.8
1992 123.2
1993 100.4
1994 92.8
1995 76.8
1996 58.1
1997 56.8
1998 59.5
1999 55.8
2000 64.1
2001 67.5
2002 70.6
2003 72.6
2004 85.3
2005 94.8
2006 93.3
2007 85.3
2008 69.2
2009 64.8
2010 71.9
2011 72.9
2012 88.8
2013 99.9
2014 115.9
2015 138.8
2016 164.4
2017 190.3

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)

Alaska 295.1
New Mexico 215.7
California 190.3
Nevada 187.8
Arizona 180.4
Colorado 153
Washington 136
Oregon 122.7
Hawaii 95.1
Utah 83.3
Montana 75
Wyoming 70.4
Idaho 58.6

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)*

Nevada 20
California 17.1
Louisiana 14.5
Georgia 14.4
Arizona 13.6
New York 11.9
Florida 11.6
North Carolina 11.2
Mississippi 10.4
Illinois 9.6
Maryland 9.5
Oklahoma 9.5
New Mexico 9.3
Washington 9.3
Alabama 8.7
Oregon 8.6
Missouri 8.3
Texas 8
Massachusetts 7.9
Arkansas 7.8
Total 9.5

* 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)

2000 1
2001 1.6
2002 3
2003 3.7
2004 3.8
2005 4.5
2006 5.1
2007 5.7
2008 5.9
2009 5.4
2010 5.5
2011 6.5
2012 7.8
2013 9.3
2014 9.9
2015 12.6
2016 15
2017 17.1

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)

Nevada 20
California 17.1
Arizona 13.6
New Mexico 9.3
Washington 9.3
Oregon 8.6
Hawaii 6.6
Colorado 5.3
Montana 4.6
Idaho 3.8
Utah 3.8
Alaska 1.8
Wyoming 0.7

HIV & Other STD Rates in California

HIV

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

HPV

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.

Chlamydia

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

Sacramento 1,177.80
Bakersfield 1,072.00
San Bernardino 1,069.50
San Francisco 1,034.00
Long Beach 906.3
Oakland 871.9
Fresno 848.7
San Diego 815.7
Stockton 796.9
Riverside 696.3

Gonorrhea

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

San Francisco 653.8
Bakersfield 441.8
Sacramento 418.9
Oakland 408.6
San Bernardino 391.6
Long Beach 355.4
Los Angeles 311.6
Fresno 296.8
Stockton 289.7
San Diego 252.6

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

San Francisco 160.9
Stockton 157.7
Bakersfield 95.9
Fresno 79.1
Long Beach 73.3
Sacramento 66.4
Los Angeles 62.8
San Diego 51.3
Oakland 49.7
Modesto 47.3

Conclusion

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.

Additional References

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.