How does someone get autoimmune disease?

Autoimmune disease. It is not fully understood and reasarch is still on . It happens in idividuals who are genetically susceptible triggered by an offending agent which could be a bacteria, virus, environemental toxins , drugs , food allergens , radiation, chemicals , hormonal to name a few . It is a flu like onset with fatigue followed by symtoms referable to the target organ, tissue or cell that is affected.
Very little. I would like to say we can vaccinate things away. But little is still known about the causation of ra, sle, and sjorgren's. We understand more the causation of psoriatic arthritis and spondylitis, but still do not have the final answers. Close, but no cookie!