In 1992, as part of a routine medical exam, Maggiore tested positive for HIV, as did a former boyfriend. Subsequently, Maggiore became involved in volunteer work for a number of AIDS charities, including AIDS Project Los Angeles, L.A. Shanti, and Women at Risk. However, following an interaction with prominent AIDS denialist Peter Duesberg in 1994, Maggiore began to question whether HIV causes AIDS. Maggiore came to believe that her positive test may have been due to influenza vaccination, pregnancy, or a common viral infection.