The purpose of notifiable conditions reporting is to provide the information necessary for public health officials to protect the public's health by tracking communicable diseases and other conditions. These data are critical to local health departments and the departments of health and labor and industries in their efforts to prevent and control the spread of diseases and other conditions. Public health officials take steps to protect the public, based on these notifications. Treating persons already ill, providing preventive therapies for individuals who came into contact with infectious agents, investigating and halting outbreaks, and removing harmful health exposures are key ways public health officials protect the public. Public health workers also use these data to assess broader patterns, including historical trends and geographic clustering. By analyzing the broader picture, officials are able to take appropriate actions, including outbreak investigation, redirection of program activities, or policy development.