Juvenile Arthritis - What Is It?
JIA essentially refers to all types of arthritis that cause joint inflammation and stiffness in a child of 16 years of age or under . Research indicates that it is an autoimmune disease, whereby white blood cells lose the ability to tell the difference between the body's own healthy cells and harmful invaders like bacteria and viruses. The immune system, which is supposed to protect the body from these harmful invaders, instead releases chemicals that can damage healthy tissues and cause inflammation and pain. |
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Doctors do not know why the immune system goes awry in children who develop JIA. Scientists suspect that it is a two-step process. First, something in a child's genetic makeup gives them a tendency to develop JIA; then an environmental factor, such as a virus, triggers the development of JIA.
Children can develop JIA at any time, though it usually starts between the ages of one and four.
There are three main classification of juvenile arthritis:
- Polyarthritis - this type affects five or more joints and is more common in girls. This type commonly affects smaller joints like the hands and feet, though larger joints may also be affected. It often seen as symmetrical; that is, it affects the same joint on both sides of the body. These children often have a more severe form of the disease, which doctors consider to be similar in many ways to adult rheumatoid arthritis.
- Oligoarthritis - this is the most common type and affects four joints or less. This type usually affects larger joints such as the knees or ankles. Girls under age 8 are most likely to develop this type of JRA. Eye disease affects about 20 – 30% of children with this type of arthritis.
- Systemic Onset - this type is the least common and affects only about 10% of children with the disease. It begins with generalized systemic symptoms which can affect internal organs (such as the heart or lungs) and parts of the body other than joints. In the past, this type was also known as Still's disease (named after an English physician Sir George F. Still (1861-1941). Arthritis may initially be overlooked because of the impressive nature of the systemic symptoms. A small percentage of these children develop arthritis in many joints and can have severe arthritis that continues into adulthood.
