JIA stands for Juvenile Idiopathic Arthritis.
JIA may be most simply defined as a long-term inflammatory disorder of the joints affecting under-16s that has no obvious cause. There are seven main types of JIA.
JIA – A Medical Description (PDF)
JIA affects approximately one out of every 1,000 people under the age of 16.
Many children and adolescents occasionally find that they have swollen, painful joints. Often this is due to some obvious cause, such a recent injury or an infection. In such cases, your doctor would not normally consider JIA.
On the other hand:
then your doctor may consider a diagnosis of JIA.
It is important to know that is no single diagnostic test for JIA. The condition is identified on the basis of a clinical assessment and a discussion of the patient’s history. Medical staff may, however, carry out a variety of tests in order to exclude other possible causes of a child’s symptoms.