Polyarticular JIA, or polyarthritis, is the second most common type of JIA and affects 5 or more joints.
It can affect a child of any age and may come on suddenly or develop gradually.
The symptoms of polyarticular JIA are similar to the symptoms of adult rheumatoid arthritis.
A child with the condition may also feel unwell and may occasionally have a high temperature of 38C or above.
Find out more about rheumatoid arthritis
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