Why do state laws require health officials to tell the state board of health about my gonorrhea?

Control its spread. This is a disease that is very contagoius and can lead to multiple medical conditions if left untreated. Partners who are not notified of the diease will continue to spread the infection to others causing even more of a epidemic.
Prevent spread. Reporting certain diseases is required by law to help prevent the spread of infection to other people and to help treat those who are exposed.