I'm not sure if spirochetes can be transmitted by saliva since I have not researched that. I do know that lyme can be transmitted sexually.
Anyway, a person does not have to be in a forest or any wooded or grassy area in order to get infected with lyme bacteria. I have known people who live in New York City where it's practically all cement and they got infected.
Did you know that ticks are not the only bug that can transmit lyme? Any vector (fleas, black flies, mosquito's, etc.) that feed on the white-footed mouse carry lyme bacteria.
Anyway, I feel bad for your friends but it's good they have you so you can give them advice. Please don't be hard on yourself as you don't have hard proof that you infected them.
Be kind to yourself okay?
12 years well ~ used Dr. Jernigan's protocol from his book about
Biological Medicine (used Borrelogen, Microbojen and Neuro-Antitox).
I still detox even though healed and drink Green Vibrance. I come back to help others for others helped me when I was sick. Pay it forward!