It is hard for families to accept that children, even babies, can be affected by arthritis.

What is Juvenile Idiopathic Arthritis?

Facts about JIA:

• It is estimated that there are over 1000 children and young people under the age of 20 years affected by arthritis in New Zealand at any one time.
• It is commonly diagnosed between ages 1 and 4, but can occur at any age before 16.
• JIA is an autoimmune illness, which is when the body’s own immune system attacks normal healthy cells instead of bacteria or viruses.
• The causes of most forms of juvenile arthritis are unknown.
• It is different from arthritis in adults. Each child has a slightly different illness and may respond differently to treatment.
• Early diagnosis and treatment means a positive outlook for a child, most children with JIA will not have active symptoms by the time they are adults.

Different Forms of JIA

Oligoarticular JIA

Polyarticular JIA (RF negative and RF positive)

Systemic JIA (Stills Disease)

Enthesitis-related arthritis

Psoriatic JIA

Undifferentiated JIA

Oligoarticluar JIA

This is the most common form of JIA, accounting for about 50% of diagnoses. It affects up to four joints, most often the knee. It commonly affects children under the age of 5, and girls more than boys. The disease may also be associated with inflammation of the eyes, especially if blood tests show the presence of an antibody called antinuclear antibody or ANA. The prognosis is generally good with 70% of children going into remission after 3–4 years. The remaining group progresses to the polyarticular form.
 

Polyarticular JIA (RF negativea d RF postive)

This disease affects more than 4 joints. It often involves the joints of the hands and feet and produces pain, swelling and stiffness. The flexor tendons of the hands may also become inflamed and there is often difficulty with writing, especially if the wrists are involved. Involvement of the lower limbs may result in difficulty with walking.
Children will often feel unwell, especially when the disease is active. Only a small number of children (about 5%, mostly older girls) are found to be rheumatoid factor (RF) positive. Polyarticular JIA RF positive usually develops in girls over 10. For these children it is important that the disease-modifying drugs are begun early to prevent joint damage.

Systemic JIA (Stills Disease)

This disease is often the most difficult to diagnose, especially as arthritis may not be present at the beginning of the illness. It can affect children at any age, but is most common in the under-5’s. It usually starts with a high fever, more troublesome in the evenings than during the day. A red, blotchy, sometimes itchy rash, more commonly seen on the arms and legs, often comes and goes with the fever. Enlargement of the glands may also occur. Children may be ill for a long time before the cause is diagnosed. Problems with the joints may develop later on. Some of these children recover after one bout of illness and suffer no long-term problems, while others have repeat ”flare-ups”, over several years. They may develop arthritis in many joints. They may also have delayed growth until their disease comes under control.

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Enthesitis-related arthritis

This form is relatively rare. It commonly affects the legs but can also cause swelling where the tendons are attached to the bones, such as the Achilles tendon at the heel or the tendons around the kneecap. This is known as 'enthesitis'. If they develop a red or painful eye at any time, this needs checking..

Psoriatic JIA

This is a rare form of arthritis, linked with the scaly skin rash of psoriasis, although the psoriasis may not develop until later. It commonly affects girls, starting at about 8–9 years. It can cause painful joints in the fingers and toes and may affect other joints too..

Undifferentiated JIA

This form is where the JIA does not fit any of the above types of JIA.

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