Microscopic polyangitis is an autoimmune disease that affects the small blood vessels of the body. Although its triggers are poorly understood, it is linked to the production of an antibody, p-ANCA, that affects those particular blood vessels. It can present with a prosaic constellation of symptoms including fever, loss of appetite, weight loss, fatigue and, in serious cases, kidney failure. Like most autoimmune diseases, there is no cure for the condition, but a course of high dose prednisone or cyclophosphamide can alleviate the symptoms and slow the progression of the disease.