How to catch them and do we know if we have one ?

STIs or STDs easily spread during unprotected sex. This occurs when you have oral sex, vaginal or anal intercourse with an infected person without using condoms. Or by sharing sex toys with that person.

You can not catch an STD by sitting on a toilet seat or in a pool.

But you can catch more than once most STIs, even if you have been treated. This is true for warts and HPV, gonorrhea, chlamydia, trichomoniasis.

Many young people who have an STI have no symptoms. In fact, for many STIs, there are up to 50% of infected people who have no symptoms. So they do not know they have an STI until they discovered during a medical examination with tests. So they can pass their infection to their partners unknowingly.