Chlamydia is the most widespread STD in the Netherlands. It’s particularly common among girls in their teens and twenties, while many of them don’t know they are infected. It’s transmitted by (anal) intercourse and oral sex.
When you have sex once with someone who is infected and don’t use a condom you have a 70% chance of getting infected. So it’s very contagious.
You get it through sex. But it can also be transmitted from mother to child during childbirth, causing serious eye infection and pneumonia.
If left untreated it can lead to PID and infection of the epididymis. This can lead to ectopic pregnancy and leave both girls and guys infertile.
It’s easy to cure with antibiotics (making the pill temporarily unreliable). If you have a relationship, both partners must be treated at the same time, even if only one has symptoms.

Symptoms with girls
Symptoms with guys