Experts say the roughly 14,000 new annual infections are mainly contracted inside the country’s borders. Fifteen years ago, new infections numbered around 9,000.

Pekka Ruuska from the infectious disease unit at Kainuu Central Hospital says men are more likely to notice signs of infection than women, who may mistake symptoms for menstruation cramps. In some women chlamydia can cause complications leading to infertility.

In Finland, the STD is most prevalent among 15–24 year-old women and 20–29 year-old men.

Women are twice as often diagnosed with the disease than men.