Definition of Juvenile rheumatoid arthritis:

Juvenile rheumatoid arthritis (JRA) is a term used to describe a common type of arthritis in children. It is a long-term (chronic) disease resulting in joint pain and swelling.

Causes, incidence, and risk factors:

The cause of JRA is not known. It is thought to be an autoimmune illness. This means the body's immune system mistakenly attacks and destroys healthy body tissue.

JRA usually occurs before age 16. Symptoms may start as early as 6 months old.

It is divided into several types:

• Systemic (bodywide) JRA involves joint swelling or pain, fevers, and rash. It is the least common type.
• Polyarticular JRA involves many joints. This form of JRA may turn into rheumatoid arthritis. It may involve five or more large and small joints of the legs and arms, as well as the jaw and neck.
• Pauciarticular JRA involves four or less joints, most often the wrists, or knees. It also affects the eyes.