Health experts see online dating as the new frontier for STD prevention — but major sites don’t want to engage.

In 2015, health officials in Rhode Island released data showing a dramatic spike in cases of syphilis (79 percent), gonorrhea (30 percent), and HIV (33 percent) in the previous year. The uptick, they said, wasn’t an outlier — it was part of a national trend. And while some of the new cases could be attributed to better testing, officials for the first time said STD rates were rising because of certain high-risk behaviors, including using online dating sites “to arrange casual and often anonymous sexual encounters.”

Since then, the trend for several STDs nationwide has only gotten worse: According to a September report from the Centers for Disease Control and Prevention, there were more than 2 million cases of chlamydia, gonorrhea, and syphilis reported in the United States in 2016 — the highest cumulative number ever recorded. “Not only are we at an all-time high,” Gail Bolan, the director of the division of STD prevention at the CDC, told me, “but we’re starting to see increases in all kind of communities.”

There are a few reasons cases of chlamydia, gonorrhea, and syphilis are on the rise. For instance, epidemiologists have documented a rise in sex without condoms among men who have sex with men.

But health experts increasingly view apps and sites such as Tinder, Grindr, and OkCupid as enablers of high-risk sex, helping people meet and hook up more efficiently than ever before. The impact of these sites is so profound they are also transforming the way health officials track and prevent outbreaks.

“We used to think about what we can do with bathhouses and sex clubs to make sure people’s risk was reduced,” said Dan Wohlfeiler, director of Read More Here