There are none.

1. Damages against B’s clinic? A does not have a contract with B’s clinic. No duties nor rights without a contract.
2. Damages against B? A does not have a contract with B. If there was a contract, we need details about it.
3. Criminal B? A and B had consensual sexual intercourse. This consent (necessarily) comprises the risk of transmission. You cannot give “consent to facts” though. Yet here B had no knowledge of his/her contagiousness. He/she definitely did not deliberately infect A. Negligence is out of question, because there is no general expectation to get regularly tested before having sex with anyone.

There are none.

1. Damages against B’s clinic? A does not have a contract with B’s clinic. No duties nor rights without a contract.
2. Damages against B?
   1. A does not have a contract with B. If there was a contract, we need details about it.
   2. Tort, § 823 Ⅰ BGB? No. B was neither negligent nor did he/she deliberately incur damage.
3. Report B as criminal? A and B had consensual sexual intercourse. This consent (necessarily) comprises the risk of transmission. You cannot give “consent to facts” though. Yet here B had no knowledge of his/her contagiousness. He/she definitely did not deliberately infect A. Negligence is out of question, because there is no general expectation to get regularly tested before having sex with anyone.