A term referring to a variety of conditions characterized by
inflammation of one or more joints. Arthritis is commonly
regarded as a disease of the elderly, but there are several
varieties that primarily affect children, including juvenile
rheumatoid arthritis, infectious arthritis, and juvenile
ankylosing spondylitis. Juvenile rheumatoid arthritis (JRA) The
most common form of arthritis in children is juvenile rheumatoid
arthritis, also known as JRA or Still's disease. Affecting over
65,000 young people in the United States—roughly 1 in 1,000—it
can affect children as young as two years old. The condition
occurs in "flareups" that can last from a few weeks to several
years, alternating with periods of remission. JRA, like other
types of arthritis, is thought to be an autoimmune disease, in
which antibodies that are supposed to protect the body from
foreign invaders turn against its own tissues, primarily the
joints. The synovium, a thin membrane surrounding the joints,
becomes inflamed, swelling and producin