The exact cause of most forms of juvenile arthritis is not well understood. Currently there is no evidence to suggest that foods, toxins, allergies or vitamin deficiencies play a role in any type of juvenile arthritis. According to most experts juvenile idiopathic arthritis (JIA) the commonest type of juvenile arthritis is caused by a combination of factors such as that is overly active immune system, viral or bacterial infections, and genetic factors.
- Autoimmune process: Juvenile arthritis is an autoimmune disorder. The healthy immune system functions to fight off harmful, foreign substances such as bacteria or viruses. But in an autoimmune disorder the body mistakenly considers some of its own cells and tissues as foreign and attacks them. The immune system inappropriately attacks joint tissues this causes inflammation as evidenced by redness, heat, pain, and swelling.
- Viral or bacterial infections: As with other autoimmune diseases, experts consider that certain viral or bacterial infection probably trigger the disease process in children with genetic makeup which makes them susceptible to juvenile arthritis. Several studies have investigated the role of bacteria such as mycoplasmas, as well as viruses such as cytomegalovirus, parvovirus, Epstein-Barr virus, and the rubella virus in juvenile arthritis. However currently there is no conclusive evidence on the role of bacteria or virus in juvenile arthritis.
- Genetic (Inherited) Factors: The risk of juvenile arthritis is probably higher in children with close relatives with JIA. In a study relatives of children with JIA were observed to have higher occurrence of other autoimmune diseases. This suggests that their genetic makeup makes them more prone to autoimmune diseases, including JIA.
Other forms of juvenile arthritis such as juvenile spondyloarthropathies (a group of diseases that affects the spine and joints of the lower extremities, most commonly the hips and knees), juvenile psoriatic arthritis (is a type of arthritis that occurs in a skin condition psoriasis), juvenile dermatomyositis (an inflammatory disease that causes muscle weakness, skin rash on the eyelids and arthritis), juvenile systemic lupus erythematosus (an autoimmune disease which causes skin rashes, arthritis, pleurisy, kidney disease and neurologic movement) are all also probably caused due to auto-immune process and genetic susceptibility.