A
- Abdominal Aortic Aneurysm — see Aortic Aneurysm
- Acanthamoeba Infection
- ACE (Adverse Childhood Experiences)
- Acinetobacter Infection
- Acquired Immune Deficiency Syndrome (AIDS) — see HIV
- Acute Flaccid Myelitis (AFM)
- Adenovirus Infection
- Adenovirus Vaccination
- ADHD [Attention Deficit/Hyperactivity Disorder]
- Adult Vaccinations
- Adverse Childhood Experiences (ACE)
- AFib, AF (Atrial fibrillation)
- African Trypanosomiasis — see Sleeping Sickness
- Agricultural Safety — see Farm Worker Injuries
- AHF (Alkhurma hemorrhagic fever)
- AIDS (Acquired Immune Deficiency Syndrome)
- Alkhurma hemorrhagic fever (AHF)
- ALS [Amyotrophic Lateral Sclerosis]
- Alzheimer's Disease
- Amebiasis, Intestinal [Entamoeba histolytica infection]
- American Trypanosomiasis — see Chagas Disease
- Amphibians and Fish, Infections from — see Fish and Amphibians, Infections from
- Amyotrophic Lateral Sclerosis — see ALS
- Anaplasmosis, Human
- Ancylostoma duodenale Infection, Necator americanus Infection — see Human Hookworm
- Angiostrongylus Infection
- Animal-Related Diseases
- Anisakiasis — see Anisakis Infection
- Anisakis Infection [Anisakiasis]
- Anthrax Vaccination
- Anthrax [Bacillus anthracis Infection]
- Antibiotic-resistant Infections
- Antibiotic and Antimicrobial Resistance
- Antibiotic Use
- see also U.S. Antibiotic Awareness Week (USAAW)
- Aortic Aneurysm
- Aortic Dissection — see Aortic Aneurysm
- Arenavirus Infections
- Arthritis
- Childhood Arthritis
- Fibromyalgia
- Gout
- Osteoarthritis (OA)
- Rheumatoid Arthritis (RA)
- Ascariasis — see Ascaris Infection
- Ascaris Infection [Ascariasis]
- Aseptic Meningitis — see Viral Meningitis
- Aspergillosis — see Aspergillus Infection
- Aspergillus Infection [Aspergillosis]
- Asthma
- Atrial fibrillation (AFib, AF)
- Attention Deficit/Hyperactivity Disorder — see ADHD
- Autism
- see also Genetics and Genomics
- Avian Influenza