This booklet, designed to provide up-to-date, accurate information, focuses on selected viral diseases that are potentially serious, often not well understood, and periodically in the news media because of their continued impact on school and community health. General information is provided on viral diseases, the immune system, vaccines, and how infections are transmitted. Diseases discussed are: viral hepatitis, hepatitis A, hepatitis B, hepatitis non-A and hepatitis non-B, herpes, cytomegalovirus, and acquired immune deficiency syndrome (AIDS). Prevention guidelines are also suggested. (CB)