Juvenile rheumatoid arthritis (JRA), sometimes
called juvenile chronic arthritis or juvenile idiopathic
arthritis, is a childhood disease that causes inflamed, swollen
joints that are often stiff and painful. Symptoms common to all forms of JRA
include joint pain, a disturbance in the way a child walks (abnormal gait), and
joint stiffness that lasts longer than 1 hour in the morning.
The cause of JRA is not well-understood. Most experts believe it is
caused by a combination of factors, including an overly active immune
system.
There are three types of JRA. Each type is based on the number of
joints affected during the first 6 months of active disease, whether the child
has other symptoms, and which parts of the body are affected:
- Pauciarticular JRA (oligoarthritis) is the most
common type of JRA. In this type, 1 to 4 joints are affected.
- Polyarticular JRA (polyarthritis) is the second most common type.
Children with this type have 5 or more joints affected.
- Systemic
JRA is the least common type. It can cause whole-body symptoms, such as fever
and rash.
