In many cases, the cause of pericarditis (both acute and chronic) is unknown. Viral infections are likely a common cause of pericarditis, although the virus may never be found. Pericarditis often occurs after a respiratory infection. Bacterial, fungal, and other infections also can cause pericarditis. Most cases of chronic, or recurring, pericarditis are thought to be the result of autoimmune disorders. Examples of such disorders include lupus, scleroderma, and rheumatoid arthritis.