STI (Sexually Transmitted Infection, formerly STD) refers to sexually transmitted infections. Most common in Switzerland: Chlamydia, gonorrhea (gonorrhea), syphilis, HIV, hepatitis B/C, HPV, genital herpes. Recommended test frequency for sex workers: Complete screening every 3 months.
Free or cheap tests at Checkpoints (Zurich, Geneva, Lausanne, Basel, Lugano), Aspasie (Geneva), Xenia (Berne), women's emergency telephone, cantonal AIDS help centers.