A common sexually transmitted infection that was substantially reduced in Costa Rica decades ago is showing signs of spreading, and societal trends related to the Millennial Generation seem to be at play.

According to a news report filed by health journalist Angie Guerrero of online news daily Costa Rica Hoy, statistics compiled by the Ministry of Public Health indicate that there was an increase of 917 cases of syphilis between 2013 and 2014.

Multiple sexual partners and a more liberal approach to sex, coupled with a tendency towards not using condoms, is a major cause of the resurgence of syphilis in Costa Rica. Sexual behavior surveys compiled by the Health Ministry reveal that six out of 10 people have two or more sexual partners at any given time of the year. Furthermore, men and women who participated in a longitudinal survey said that they have an average of ten sexual encounters per month, and that unprotected sex was the norm.

Adults in Costa Rica are more likely to be monogamous, have less sex and use more protection than their younger counterparts. Members of the Millennial Generation are starting having sex earlier than ever; the current average is 15 years old, and they are more likely to be more adventurous in terms of seeking multiple partners or sharing them. Teenagers in Costa Rica tend to forego protection such as condoms until they are older.

Syphilis is a disease caused by the treponema pallidum spirochete bacterium. According to WebMD, this is a highly contagious disease:

[Syphilis is] spread primarily by sexual activity, including oral and anal sex. Occasionally, the disease can be passed to another person through prolonged kissing or close bodily contact. Although this disease is spread from sores, the vast majority of those sores go unrecognized. The infected person is often unaware of the disease and unknowingly passes it on to his or her sexual partner.