Age Groups Persons 25 Diseases 18 Child 12 Health Care 9 Adult 8 Immune System Diseases 8 Infant 8 Pathological Conditions, Signs and Symptoms 7 Adolescent 6 Diagnostic Techniques and Procedures 6 HIV Infections 6 Health Services Administration 6 Immunologic Deficiency Syndromes 6 Lentivirus Infections 6 RNA Virus Infections 6 Retroviridae Infections 6 Sexually Transmitted Diseases 6 Sexually Transmitted Diseases, Viral 6 Virus Diseases 6 Health & Biological Sciences 5 Signs and Symptoms 5 Behavior 4 Behavior and Behavior Mechanisms 4 Environment and Public Health 4 Nutritional and Metabolic Diseases 4 Public Health 4 Crime 3 Criminology 3 Health Care Quality, Access, and Evaluation 3