If you've had chickenpox, the varicella-zoster virus is still present in your nerve cells. It never dies, and it might remain dormant for years. Even though you are no longer at danger of reinfection with the chickenpox virus, you are still vulnerable to another disease: shingles. People who have had chickenpox can develop this illness up to seven years after their first infection. The most common cause of arthritis in children is juvenile rheumatoid arthritis (JRA). JRA is a chronic condition that can lead to joint damage or loss if not treated. There are several types of JRA but they all involve the immune system attacking the joints. The most common type of JRA is known as systemic juvenile arthritis (SJA). SJA affects many parts of the body but most patients experience pain, stiffness, and swelling in one or more of their joints. Arthritis of the elbow, knee, hand, foot, back, neck, or jaw may occur. Children with SJA may have symptoms such as fever, fatigue, rash, mouth sores, eyesight changes, abdominal pain, diarrhea, and constipation. A diagnosis of SJA requires a blood test showing high levels of inflammation markers in the blood and magnetic resonance imaging (MRI) or computerized tomography (CT) scans of the brain and spinal cord to look for signs of organ involvement.