- Abdominal Aortic Aneurysm
- Acanthamoeba Infection
- ACE (Adverse Childhood Experiences)
- Acinetobacter Infection
- Adenovirus Infection
- ADHD [Attention Deficit/Hyperactivity Disorder]
- AFib, AF (Atrial fibrillation)
- African Trypanosomiasis
- AHF (Alkhurma hemorrhagic fever)
- Alkhurma hemorrhagic fever (AHF)
- ALS [Amyotrophic Lateral Sclerosis]
- Alzheimer’s Disease
- Amebiasis, Intestinal [Entamoeba histolytica infection]
- American Trypanosomiasis [Chagas Disease]
- Anaplasmosis, Human
- Ancylostoma duodenale Infection, Necator americanus Infection
- Angiostrongylus Infection
- Anisakiasis
- Anthrax [Bacillus anthracis Infection]
- Antibiotic and Antimicrobial Resistance
- Arenavirus Infection
- Arthritis
- Childhood Arthritis
- Fibromyalgia
- Gout
- Osteoarthritis (OA)
- Rheumatoid Arthritis (RA)
- Aseptic Meningitis
- Aspergillus Infection [Aspergillosis]
- Asthma
- Autism
- Avian Influenza