SAN FRANCISCO (KRON) – Rates of sexually transmitted diseases among older Californians skyrocketed in the last decade, according to a report from based on data from the U.S. Centers for Disease Control and Prevention.

Rates of gonorrhea infection went up 465.6% between 2010 and 2019 among Californians 55 and older, the report states. The chlamydia rate rose 238.4%, and the prevalence of human immunodeficiency virus infection went up 84.3%.

Nationwide, rates of gonorrhea went up 383%, rates of chlamydia went up 200% and the prevalence of HIV infection went up 92% among the same age group in the same time period.

The study looked at rates in all states and found that Arkansas’ 88% increase in gonorrhea cases was the smallest in the United States. The biggest increase was in South Dakota: a 1,393.4% increase. As a matter of fact, the Mount Rushmore State was the only state to rank inside the top 10 for gonorrhea, chlamydia and HIV.

But why is this happening? says “possible reasons for the trend may vary.”

“Divorce rates among those 55 and over are on the rise, which lends itself to a potentially higher diversity of sexual partners among the demographic,” is one explanation the website gives. Others include that “medications have enabled both men and women to remain sexually active later in life,” “menopause causes a thinning of vaginal tissues, which can increase susceptibility to STDs,” and “many older adults may not have received the same safe sex education in school that younger generations have.”

Researchers believe that because people over 55 are unlikely to get pregnant, condom use may fall off after menopause.

The CDC urges people to get screened, and also provides increased screening as a possible explanation for the increases.

“As both chlamydial and gonococcal infections can be asymptomatic, the number of infections identified and reported can increase as more people are screened – even when incidence is flat or decreasing,” the CDC states. “Consequently, increasing case rates over time may reflect more complete reporting, as well as increases in incidence of infection, screening coverage, and use of more sensitive tests. Likewise, decreases in case rates may suggest decreases in incidence of infection or screening coverage.”

The CDC provides a zip code-based search of STD testing centers.