There was still no solid proof that AIDS was caused by a virus at all. But three kinds of evidence pointed that way, and Montagnier recalls them in his memoir, a book titled Virus. First, the incidence of AIDS among homosexuals linked by sexual interactions suggested that it was an infectious disease. Second, the incidence among intravenous drug users suggested a blood-borne infectious agent. Third, the cases among hemophiliacs implied a blood-borne agent that escaped detection in processed blood products such as clotting factor. So: It was infinitesimal, contagious, blood-borne.
