An allergic reaction to meat-based meals had researchers stumped — until they connected the condition to bites from certain ticks.
Disease
Alzheimer's disease
Understand more about this brain disease that is the most common cause of dementia. Also learn about new tests and medicines.
Disease
Ameloblastoma
Learn more about the symptoms and treatment of this rare, noncancerous (benign) tumor that develops in the jaw.
Disease
Amenorrhea
Absence of menstruation (amenorrhea) may be linked to an underlying, treatable problem. Learn about amenorrhea causes and when to seek help.
Disease
Amnesia
Read about what can cause memory loss and learn steps you can take to manage it.
Disease
Ampullary cancer
Learn more about the causes, diagnosis and treatments for cancer of the ampulla of Vater.
Disease
Amyloidosis
This rare disease can affect different organs in different people. Find out how early and accurate diagnosis can lead to better outcomes.
Disease
Amyotrophic lateral sclerosis (ALS)
This progressive nervous system disease, also known as Lou Gehrig's disease, destroys nerve cells.
Disease
Anal cancer
Learn about this cancer that affects the anal canal and causes bleeding and pain. Treatment is usually with a combination of radiation and chemotherapy.
Disease
Anal fissure
Learn what causes a tear in the anus and how to prevent or treat this often painful condition.
Disease
Anal fistula
An infected anal gland can sometimes cause a tunnel to develop between the skin and the anus. Learn about symptoms and diagnosis for this painful, but treatable, condition.
Disease
Anal itching
Learn about the causes, treatment and self-care tips for this common, sometimes embarrassing condition.