Inclusion Criteria:  For index patients  Diagnosed with at least one bacterial STI, and/or HIV and/or acute HCV at one of the participating centers during the study period, Aged >= 18, Agree to participate in the study after oral and written information.  For notified partners  Attend one of the participating centers during the study period, within 6 months of being notified of their exposure to an STI (bacterial STI, and/or HIV and/or acute HCV) by one of their partners, who is infected with one or more of these STIs, Aged >= 18, Agree to participate in the study after oral and written information.  Non-Inclusion Criteria:  For index patients and notified partners  People who do not read or speak French, Wardship or curatorship adults.