Kids with siblings have less arthritis

Children with brothers and sisters are less likely to develop juvenile arthritis, a study suggests.

Victorian researchers believe this may be because kids with siblings are more likely to be exposed to childhood infections, which builds an immune system that's less susceptible to arthritis.

Juvenile arthritis affects around 6000 Australian children.

Most forms of the illness are believed to be autoimmune disorders, where the body's immune system attacks its own tissues.

For the study Murdoch Childrens' Research Institute scientists compared more than 300 children with arthritis to more than 1000 children without it.

"Our study showed exposure in the first six years of life to siblings may decrease the risk of juvenile arthritis," said lead researcher Dr Justine Ellis.

"This could be due to the fact that contact with siblings may provide protection by exposing children to infections and germs and building an immune system less susceptible to the development of juvenile arthritis."

Dr Ellis said the findings provide further support for a role of the "hygiene hypothesis" in combination with genetic factors in the development of juvenile arthritis.