Persons Age Groups 25 Diseases 18 Health Care 14 Child 12 Adult 8 Immune System Diseases 8 Infant 8 Diagnostic Techniques and Procedures 7 Health Services Administration 7 Pathological Conditions, Signs and Symptoms 7 Adolescent 6 HIV Infections 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 Behavior and Behavior Mechanisms 5 Health & Biological Sciences 5 Health Care Quality, Access, and Evaluation 5 Signs and Symptoms 5 Social Sciences 5 Sociology 5 Behavior 4 Environment and Public Health 4 Health Care Economics and Organizations 4 Medicine 4