The British Association for Sexual Health and HIV reported that the use of dating applications has led to increasing rates of syphilis and gonorrhea.

Dating apps such as Tinder and Happn have gained widespread popularity in the United Kingdom in recent years. These are designed to help their users find everything from long-term romantic relationships to casual sexual encounters. According to the Online Dating Association, between 25 to 40 percent of current relationships in the UK are developed through such apps.

This has coincided with the rise in STDs. Public Health England recorded that the number syphilis cases rose 33 percent and gonorrhea increased 19 percent in 2014 over 2013.

According to the BBC, the head of Happn—one of the UK’s most popular dating apps—believes that dating “apps are following wider social trends and changing behaviors that have been unfolding for decades.” She purports that “a liberalization of attitudes towards the number of partners, the status of relationships, towards marriage, divorce, etc.” is the underlying cause of the problem.

A similar trend is occurring in the United States, where, based on federal data, cases of chlamydia, gonorrhea and syphilis all hit record highs in 2015. Some U.S. healthcare experts contend that this is largely driven by online dating apps, as they “lead to more casual sex among people 25 and younger, who are the most likely to be infected and also the least inclined to seek testing,” the Los Angeles Times reported.